MCAT Chem
mass percentage
(mass of solute/mass of solution) x 100%
HBrO3
bromic acid
specific heat capacity
is the quantity of heat required to raise the temperature of one gram of a substance by one degree Celsius (or one kelvin) at constant pressure
thermochemical equation
is the chemical equation for a reaction (including phase labels) in which the equation is given a molar interpretation, and the enthalpy of reaction for these molar amounts is written directly after the equation
Potential energy
is the energy an object has by virtue of its position in a field of force
Kinetic energy
is the energy associated with an object by virtue of its motion
Thermodynamics
is the science of the relationships between heat and other forms of energy.
Hunds rule
one electron per orbital of equivalent energy before doubling up
volatile
readily changing to a vapor; changeable; fickle; explosive
...
redox reaction questions
Boyles law
who's law is this
Charles law
whos law is this
...
write the three equations
...
writing acid base reactions
percentage yield
yield/theoretical yield x 100
law of definite proportions
(chemistry) law stating that every pure substance always contains the same elements combined in the same proportions by weight
spontaneity
(n) impulsive action
pka
-logka, acid dissociation constant
Heat
..., thermal energy that flows from a warmer material to a cooler material
compound
1
14.7 psi
1 atm - how much psi
101,325
1 atm = how many Pa...
29.92
1 atm = how much Hg
760 mmHg
1 atm equals how much mmHg
4.184 J
1 cal = ______ J
exact
1 foot = 12 inches exact or uncertain
1000
1 liter is equivalent to ________ grams.
second order reaction
a reaction whose rate depends on the concentration of one reactant raised to the second power or on the concentrations of two different reactants, each raised to the first power
systematic error
a repeated error which affects every measurement to the same degrees - caused by a technique problem or instruments.
combustion
The body generates energy from food by the same overall process as _________________ so the overall enthalpy change is the same as the heat of _____________
energy
The capacity to do work or produce heat
common ion effect
The phenomenon in which the addition of an ion common to two solutes brings about precipitation or reduced ionization, Ex: AgCl in water If you add in NaCl (more Cl ion) then LESS solid will dissolve at equilbirum Application of Le Chatelier DECREASES solubility
spontaneous process
a process that can occur without an input of energy, a process that occurs without outside intervention
extensive property
a property that depends on the amount of matter that is present
intensive property
a property that does not depend on the amount of matter present
compound
a pure substance made of two or more elements chemically combined
first order reaction
a reaction in which the reaction rate is proportional to the concentration of only one reactant
exothermic reaction
a reaction that releases energy in the form of heat
law
a rule or body of rules of conduct inherent in human nature and essential to or binding upon human society
monomer
a simple molecule that can combine with other like or unlike molecules to make a polymer
microstate
a single possible arrangement of the positions and kinetic energies of gas molec in a system
aqueous solution
a solution in which water is the solvent
weak electrolyte
a solution that conducts electricity poorly because only a fraction of the solute exists as ions
functional group
a specific configuration of atoms commonly attached to the carbon skeletons of organic molecules and usually involved in chemical reactions
heterogeneous equilibrium
a state of equilibrium that occurs when the reactants and products of a reaction are present in more than one physical state
random error
a statistical fluctuation that occurs because of chance variation in the elements selected for a sample
electron
a subatomic particle that has a negative charge
electrolyte
a substance that dissolves in water to give a solution that conducts electric current
atomic theory
a theory that states that all matter is composed of tiny particles called atoms.
true
a weak acid by itself isnt strong enough to be a buffer and vice versa for weak bases
acidosis
abnormally high acidity (excess hydrogen-ion concentration) of the blood and other body tissues
acid base reaction
acid + base -----> salt + water
Al(OH)3
aluminum hydroxide
NH3
ammonia
stock solution
an accurately prepared solution of known concentration that can be diluted to make solutions of lower concentration
oxoacid
an acid that contains oxygen in addition to hydrogen and another element
nonmetal
an element that lacks most of the properties of a metal
H H equation
an equation that allows use to quickly find the ph of a buffer from the initial morality only if x is small
...
applying solubility rules of ionic compounds to problems
chemical reaction
breaking of old and formation of new chemical bonds that result in new substances
HBrO2
bromous acid
nuclear forces
the interaction that binds protons and neutrons, protons and protons, and neutrons and neutrons together in a nucleus
molar mass
the mass in grams of one mole of a substance
theoretical yield
the maximum amount of product that could be formed from given amounts of reactants
actual yield
the measured amount of a product obtained from a reaction
mass percent
the percent by mass of a component of a mixture or of a given element in a compound.
nucleus
the positively charged dense center of an atom
energy
the potential or capacity to move matter
principal quantum number
the quantum number that indicates the energy and orbital of an electron in an atom.
magnetic quantum number
the quantum number that indicates the orientation of an orbital around the nucleus, Symbolized by m, indicates the orientation of an orbital around the nucleus.
angular quantum number
the quantum number that indicates the shape of the orbital
zero order reaction
the rate of this reaction does not depend on the concentration of any of the reactants
limiting reactant
the reactant that limits the amount of product that can form in a chemical reaction
limiting reactant
the reactant that runs out first
law of mass action
the rules by which the equilibrium constant is expressed in terms of the concentrations of reactants and products, in accordance with the balanced chemical equation for the reaction.
reference form
the stablest form (physical state and allotrope) of the element under standard thermodynamic conditions
molecular mass
the sum of the masses of all atoms in a molecule
mass number (A)
the sum of the number of neutrons and protons in an atomic nucleus
...
titration problem
It is not possible
to make thermal measurements on individual ions
standard state
to the standard thermodynamic conditions chosen for substances when listing or comparing thermodynamic data: 1 atm pressure and the specified temperature (usually 25C).
heat tax
unavoidable cut of every energy transaction in nature
stoichiometry
unit conversion process involving mole equalities.
rate order
usually determined experimentally
true
velocity of an electron is related to the wave function
H2O
water
zero
we must arbitrarily define the standard enthalpy of formation of one ion as
buffers
weak acids or conjugate bases that can react with strong acids or bases to prevent sharp, sudden changes in pH
theory
well-tested explanation that unifies a broad range of observations
carbonic acid neutralize base
what is happenining here
...
what is the mole fraction eqaution
pressure is inversely related to volume.
what is the relation ship between pressure and volume
complete ionic equation
what is this
molecular formula
what kind of formula
uses balls to represent atoms and sticks to represent chemical bonds
what kind of formula
a weak acid and its conjagate base
what must a buffer contain significant amounts of
gas sample because manometer fluid is excess left
what pressure is larger the atmospheric pressure or gas sample pressure
a monometer
what type of instrument is this
a precipitate reaction
what type of reaction
it will neutralize only if the strong base is amount is less
what would occur to the solution
density of a gas equation
which equation
mixture of pressure equation
which equation
This is the ideal gas law
which law is this
Avogadro law
who's law is this
the heat of reaction at constant pressure.
The enthalpy of reaction equals
H = U + PV
The equation for enthalpy equals to
surroundings
are everything in the vicinity of the thermodynamic system
2
atomic radia increase which dirrection
metalloid
An element that tends to have properties that are similar to those of metals and nonmetals
dichromate
Cr₂O₇⁻²
isotope
atoms of the same element that have different numbers of neutrons
...
balancing equations with solubility skills and writing chemical reactions
covalent bond
bond formed by the sharing of electrons between atoms
polyprotic acid
is an acid that yields two or more acidic hydrogens per molecule
fractional abundance
The fraction of the total number of atoms that is composed of a particular isotope.
internal energy
The grand total of all energies inside a substance
relative short supply
The major problem with petroleum and natural gas as fuels is their
percentage composition
The mass percentages of each element in a compound
2.2g/L
The molar mass of a certain gas is 49g. What is the density of the gas in g/L at STP?
balanced
__Mg + __Cl₂ --> __MgCl₂
balanced
__MgO + __SO₃ --> __MgSO₄
2, 1, 2, 1
__Na + __MgF₂ --> __NaF + __Mg
1, 1, 2
__N₂ + __O₂ --> __NO
1, 2, 1, 1
__Sn + __HF --> __SnF₂ + __H₂
ionic bond
a chemical bond resulting from the attraction between oppositely charged ions.
fuel
is any substance that is burned or similarly reacted to provide heat and other forms of energy.
molarity (M)
is defined as the moles of solute dissolved in one liter (cubic decimeter) of solution
Heat
is denoted by the symbol q.
Thermochemistry
is one area of thermodynamics
metal
a class of elements characterized by physical properties that include shininess, malleability, ductility, and conductivity
chemical formula
a combination of chemical symbols and numbers to represent a substance
ionic compound
a compound composed of positive and negative ions
allotrope
is one of two or more distinct forms of an element in the same physical state
binary compound
a compound composed of the ions of one metal element and ions of on non-metal element, joined by ionic bonds, compound that is composed of two elements
hydrate
a compound that contains water of hydration
hydrate
a compound that has a specific number of water molecules bound to each formula unit
ionic compound
a compound that results when a metal reacts with a nonmetal to form cations and anions
integrated rate law
an expression that shows the concentration of a reactant as a function of time
hemaglobin
an ion containing protein that transports the bulk of oxygen that is carried in the blood
spectator ion
an ion that appears on both sides of an equation and is not directly involved in the reaction
polyatomic ion
an ion that is made of more than one atom
nucleon
any particle present in the nucleus of an atom, that is, a proton or neutron.
silver
Ag⁺¹
no
does the size of an atom always relate to its position on the periodic table
pH = pKa + log10{[base]/[acid]} and so log10{[base]/[acid]}= pH - pKa = 7.40 - {- log10(2.9 x 10-8)} = - 0.138 and so (taking the inverse log10 of both sides of this equation) {[base]/[acid]} = 10-0.138 = 0.728 [base] = 0.728 [acid] = 0.728 (0.2000 M) = 0.1457 M Since potassium hypochlorite is a strong electrolyte (completely ionizes in water), then moles KClO = 1.000 L 0.1457 mol = 0.1457 mol 1.000 L grams KClO = 0.1457 mol 90.55 g = 13.2 g 1.00 mol ,
1) A chemist has a 0.2000 M stock solution of hypochlorous acid (HClO, a weak acid, with Ka = 2.9 x 10-8) and solid potassium hypochlorite (KClO, M = 90.55 g/mol), a strong electrolyte containing the conjugate base of hypochlorous acid. How many grams of KClO must be added to 1.000 L of the stock HClO solution to form a buffer solution with pH = 7.40? You may assume that the volume of the solution does not change when KClO is added. [12 points]
a. weak acid, strong base b.point B c.point C d.o-cresonphthalein pKa = 9.0
1) The following questions refer to the titration curve given below. For each of the following questions circle the correct answer. There is one and only one correct answer per question. [3 points each] a) The titration curve shows the titration of a strong acid a weak acid a strong base a weak base with a strong base with a strong base with a strong acid with a strong acid b) Which point on the titration curve represents a region where a buffer solution has formed? point A point B point C point D c) Which point on the titration curve represents the equivalence point? point A point B point C point D d) Which of the following would be the best indicator to use in the titration? erythrosin B methyl red bromthymol blue o-cresonphthalein pKa = 2.9 pKa = 5.4 pKa = 6.8 pKa = 9.0
d
1) Which of the following reactions will go essentially to completion? a) Reaction of a strong acid with a strong base b) Reaction of a strong acid with a weak base c) Reaction of a weak acid with a weak base d) Both a and b e) Both a and b and c
1. element 2. molecule 3. molecular 4. ionic 5. formula unit
1-5
1 atomic mass unit
1.66 x 10 ^ -27 kg
Entropy increases by a small amount as one goes from solid to liquid, and by a large amount as one goes from liquid to gas.
12) What happens to the entropy of a sample of matter when it changes state from a solid to a liquid? From a liquid to a gas?
16) Any metal below the H+/H2 half-cell reduction potential, at 0.00 v, would be expected to dissolve in HCl (hydrochloric acid) for standard conditions. This is because when the half-cell oxidation potential for the metal (found by reversing the reaction and changing the sign of the potential) is combined with the half-cell reduction potential for H+/H2, a positive voltage will result, indicating a spontaneous reaction.
16) How can Table 18.1 be used to predict whether or not a metal will dissolve in HCl? In HNO3?
antoine lavoisier
18th century scientist who discovered the law of conservation of mass
1 torr
1mmHg equals how much torr
elements
2
2) Define the following terms [4 points each] a) endpoint The point in a titration where the indicator being used changes color. One tries to choose an indicator whose end point is as close as possible to the equivalence point of the titration.
2) Define the following terms [4 points each] a) endpoint
b) selective precipitation The process where a substance is added to a solution that causes one solute in the solution to form a solid (precipitate) while the remaining solutes remain in solution. The precipitate can then be removed by filtration. Selective precipitation therefore is a method that can separate a particular solute from a mixture of solutes in a solution.
2) Define the following terms [4 points each] b) selective precipitation
A buffer is a solution that is resistant to changes in pH. Buffers work by converting strong acids or bases into weak acids or bases. Consider a buffer that contains a weak acid (HA) and its conjugate base (A-). If we add a strong acid like HCl, or a strong base like NaOH, the reactions that occur are as follows HCl(aq) + A-(aq) ® HA(aq) + Cl-(aq) NaOH(aq) + HA ® H2O(l) + A-(aq)
2) What is a buffer? How does a buffer work? How does it neutralize added acid? Added base?
e
2) Which of the following aqueous solutions would be a buffer solution? a) A solution that has 0.100 M HNO2 (a weak acid) and 0.100 M NO2- b) A solution that has 0.100 M HClO4 (a strong acid) and 0.100 M ClO4- c) A solution that has 0.100 M NH3 (a weak base) and 0.100 M NH4+ d) Both a and b e) Both a and c
exact
202 students is this exact or not?
...
27) In which of these solutions will HNO2 ionize less than it does in pure water? a) 0.10 M NaCl b) 0.10 M NaOH c) 0.10 M KNO3 d) 0.10 M NaNO2
mixture
3
For a buffer, pH = pKa + log10{[base]/[acid]} But [acid] = 2 [base], and so pH = - log10(1.8 x 10-4) + log10 (1/2) = 3.44
3) A buffer solution is formed using formic acid (HCOOH, Ka = 1.8 x 10-4) and formate ion (HCOO-). The concentration of formic acid in the buffer solution is twice the concentration of formate ion. What is the pH of the buffer solution? [4 points]
a
3) Consider the titration of H3PO4, a weak polyprotic acid, with Ba(OH)2, a strong base. The number of equivalence points that will be observed in this titration is a) 3 b) 2 c) 1 d) 0 e) None of the above
4) In a voltaic cell (also called a galvanic cell or a battery) a chemical reaction is used to generate a voltage. In an electrolytic cell an external voltage is used to force a chemical reaction to occur in a particular direction
4) Explain the difference between a voltaic (or galvanic) electrochemical cell and an electrolytic one.
4) The Henderson-Hasselbach equation is pH = pKa + log10{[base]/[acid]} It is useful in preparing a buffer solution with a particular value for pH.
4) What is the Henderson-Hasselbalch equation and why is it useful?
7.1 x 10^5 Joules, 1.7 x 10^5 cal
6.43 A car whose mass is 4.85 x 10^3 lb is traveling at a speed of 57 miles per hour. What is the kinetic energy of the car in joules? in calories?
40) In all cases we will use the procedure discussed in class. We will first find balanced half-cell oxidation and reduction half-reactions. We will multiply one or both reactions by an integer value so that the number of electrons transferred will cancel when the half-reactions are combined. Finally, we will combine the half-reactions and cancel any substances appearing as both reactants and products to obtain the final balanced net cell reaction. a) ox 2 I-(aq) ® I2(s) + 2 e- red NO2-(aq) + 2 H+(aq) + e- ® NO(g) + H2O(l) x 2 net 2 I-(aq) + 2 NO2-(aq) + 4 H+(aq) ® I2(s) + 2 NO(g) + 2 H2O(l) b) Note - I will go ahead and do this problem. However, I would not give a problem like this on an exam where the same element has four different oxidation states, because there is some ambiguity as to which half-reactions are correct. ox 2 Cl-(aq) ® Cl2(g) + 2 e- red ClO4-(aq) + 2 H+(aq) + 2 e- ® ClO3-(aq) + H2O(l) net 2 Cl-(aq) + ClO4-(aq) + 2 H+(aq) ® Cl2(g) + ClO3-(aq) + H2O(l) c) ox Sn2+(aq) ® Sn4+(aq) + 2 e- x 3 red NO3-(aq) + 4 H+(aq) + 3 e- ® NO(g) + 2 H2O(l) x 2 net 3 Sn2+(aq) + 2 NO3-(aq) 8 H+(aq) ® 3 Sn4+(aq) + 2 NO(g) + 4 H2O(l)
40) Balance each redox reaction occurring in acid aqueous solution. a) I-(aq) + NO2-(aq) ® I2(s) + NO(g) b) ClO4-(aq) + Cl-(aq) ® ClO3-(aq) + Cl2(g) c) NO3-(aq) + Sn2+(aq) ® Sn4+(aq) + NO(g)
42) Balancing oxidation-reduction reactions for bas conditions is exactly the same as balancing the reactions for acid conditions (problem 40) except that there is one additional step where OH- ions are added, if necessary, to convert all H+ ions into water molecules. a) ox Br-(aq) + 3 H2O(l) ® BrO3-(aq) + 6 H+(aq) + 6 e- red MnO4-(aq) + 4 H+(aq) + 3 e- ® MnO2(s) + 2 H2O(l) x 2 Br-(aq) + 2 MnO4-(aq) + 2 H+(aq) ® BrO3-(aq) + 2 MnO2(s) + H2O(l) add OH- 2 OH-(aq) ® 2 OH-(aq) net Br-(aq) + 2 MnO4-(aq) + H2O(l) ® BrO3-(aq) + 2 MnO2(s) + 2 OH-(aq) b) This one is tricky. I would likely not ask this sort of problem on an exam. ox Ag(s) + 2 CN-(aq) ® Ag(CN)2-(aq) + e- x 4 red O2(g) + 4 H+(aq) + 4 e- ® 2 H2O(l) 4 Ag(s) + 8 CN-(aq) + O2(g) + 4 H+(aq) ® 4 Ag(CN)2-(aq) + 2 H2O(l) add OH- 4 OH-(aq) ® 4 OH-(aq) net 4 Ag(s) + 8 CN-(aq) + O2(g) + 2 H2O(l) ® 4 Ag(CN)2-(aq) + 4 OH-(aq) c) ox Al(s) + 2 H2O(l) ® AlO2-(aq) + 4 H+(aq) + 3 e- x 2 red NO2-(aq) + 7 H+(aq) + 6 e- ® NH3(g) + 2 H2O(l) 2 Al(s) + NO2-(aq) + 2 H2O(l) ® 2 AlO2-(aq) + NH3(g) + H+(aq) add OH- OH-(aq) ® OH-(aq) net 2 Al(s) + NO2-(aq) + H2O(l) + OH-(aq) ® 2 AlO2-(aq) + NH3(g)
42) Balance each redox reaction occurring in base aqueous solution. a) MnO4-(aq) + Br-(aq) ® MnO2(s) + BrO3-(aq) b) Ag(s) + CN-(aq) + O2(g) ® Ag(CN)2-(aq) c) NO2-(aq) + Al(s) ® NH3(g) + AlO2-(aq)
46) a) ox Mg(s) ® Mg2+(aq) + 2 e- E° = + 2.37 v red Ni2+(aq) + 2 e- ® Ni(s) E° = - 0.23 v net Ni2+(aq) + Mg(s) ® Ni(s) + Mg2+(aq) E°net = + 2.14 v b) ox Fe(s) ® Fe2+(aq) + 2 e- E° = + 0.45 v red 2 H+(aq) + 2 e- ® H2(g) E° = 0.00 v net 2 H+(aq) + Fe(s) ® H2(g) + Fe2+(aq) E°net = + 0.45 v c) ox 3 Cu(s) ® 3 Cu2+(aq) + 6 e- E° = - 0.34 v red 2 NO3-(aq) + 8 H+(aq) + 6 e- ® 2 NO(g) + 4 H2O(l) E° = + 0.96 v net 2 NO3-(aq) + 8 H+(aq) + 3 Cu(s) ® 2 NO(g) + 4 H2O(l) + 3 Cu2+(aq) E°net = + 0.62 v
46) Calculate the standard cell potential for each of the following electrochemical cells. a) Ni2+(aq) + Mg(s) ® Ni(s) + Mg2+(aq) b) 2 H+(aq) + Fe(s) ® H2(g) + Fe2+(aq) c) 2 NO3-(aq) + 8 H+(aq) + 3 Cu(s) ® 2 NO(g) + 4 H2O(l) + 3 Cu2+(aq)
50) a) Mg(s)|Mg2+(aq)||Ni2+(aq)|Ni(s) b) Fe(s)|Fe2+(aq)||H+(aq)|H2(g), Pt c) Cu(s)|Cu2+(aq)||NO3-(aq)|NO(g), Pt
50) Represent each of the electrochemical cells in problem 46 by a cell diagram, using standard cell notation (see Tro, pp 822-823). 46) Calculate the standard cell potential for each of the following electrochemical cells. a) Ni2+(aq) + Mg(s) ® Ni(s) + Mg2+(aq) b) 2 H+(aq) + Fe(s) ® H2(g) + Fe2+(aq) c) 2 NO3-(aq) + 8 H+(aq) + 3 Cu(s) ® 2 NO(g) + 4 H2O(l) + 3 Cu2+(aq)
53) There are two ways in which we can do this sort of problem. We could calculate the net cell potential (as in problem 46), and then use the fact that for spontaneous processes the net cell potential will be positive. Alternatively, we can use the position of the half-cell reactions in Table 18.1. If the substance being reduced in the reaction is higher in Table 18.1 than the substance being oxidized then the reaction is spontaneous. In this problem I will use the second method, but I will also give the net cell potential (although not the oxidation, reduction, and net cell reactions). a) Zn2+/Zn is below Ni2+/Ni, and so not spontaneous. E° = - 0.53 v b) Pb2+/Pb is above Ni2+/Ni, and so spontaneous. E° = + 0.10 v c) Ag+/Ag is above Al3+/Al, and so spontaneous. E° = + 2.46 v d) Mn2+/Mn is below Pb2+/Pb, and so not spontaneous. E° = - 1.05 v
53) Which of the redox reactions do you expect to occur spontaneously in the forward direction (for standard conditions)? a) Ni(s) + Zn2+(aq) ® Ni2+(aq) + Zn(s) b) Ni(s) + Pb2+(aq) ® Ni2+(aq) + Pb(s) c) Al(s) + 3 Ag+(aq) ® Al3+(aq) + 3 Ag(s) d) Pb(s) + Mn2+(aq) ® Pb2+(aq) + Mn(s)
Avogadro's number
6.022 x 10^23. The number of particles in exactly one mole of a pure substance
small car reason: (1/2)mv^2 = kinetic energy (.50)(1)(2)^2 = 2 small car (.50)(2)(1)^2 = 1 large car
6.31 A small car is traveling at twice the speed of a larger car,which has twice the mass of the smaller car. Which car has the greater kinetic energy? (Or do they both have the same kinetic energy?)
(a) negative (b) solid (c) higher than final enthalpy (d) -20C
6.33 A 250-g sample of water at 20.0C is placed in a freezer that is held at a constant temperature of -20.0C. Considering the water as the "system," answer the following questions: a. what is the sign of q(sys) for the water after it is placed in the freezer? b. After a few hours, what will be the state of the water? c. How will the initial enthalpy for the water compare with the final enthalpy of the water after it has spent several hours in the freezer?. d. What will the temperature of the water be after several hours in the freezer?
(a) A (b) A
6.37 You have two samples of different metals, metal A and metal B, each having the same mass. You heat both metals to 95C and then place each one into separate beakers containing the same quantity of water at 25C. a. You measure the temperatures of the water in the two beakers when each metal has cooled by 10C and find that the temperature of the water with metal A is higher than the temperature of the water with metal B. Which metal has the greater specific heat? Explain. b. After waiting a period of time, the temperature of the water in each beaker rises to a maximum value. In which beaker does the water rise to the higher value, the one with metal A or the one with metal B? Explain.
-106.4 kcal
6.41 Methane, CH4, is a major component of marsh gas. When 0.5000 mol methane burns to produce carbon dioxide and liquid water, 445.1 kJ of heat is released. What is this heat in kilocalories?
ion
An atom or group of atoms that has a positive or negative charge
endothermic; + 66.2 kJ
6.49 Nitric acid, a source of many nitrogen compounds, is produced from nitrogen dioxide. An old process for making nitrogen dioxide employed nitrogen and oxygen. N2(g) + 2O2(g) = 2NO2(g) The reaction absorbs 66.2 kJ of heat per 2 mol NO2 produced. Is the reaction endothermic or exothermic? What is the value of q?
63) The best oxidizing agent will be the species that has the largest (most positive) reduction potential. Based on Table 18.1 Pb2+/Pb E° = - 0.13 v Cr3+/Cr E° = - 0.73 v Fe2+/Fe E° = - 0.45 v Sn2+/Sn E° = - 0.14 v So Pb2+ is the best oxidizing agent.
63) Which metal cation is the best oxidizing agent? a) Pb2+ b) Cr3+ c) Fe3+ d) Sn2+
64) The best reducing agent will be the species that has the largest (most positive) oxidation potential. Note that to get the oxidation potential we have to reverse the reduction reaction, and so change the sign of the potential. Mn/Mn2+ E° = + 1.18 v Al/Al3+ E° = + 1.66 v Ni/Ni2+ E° = + 0.23 v Cr/Cr3+ E° = + 0.73 v So Al is the best reducing agent
64) Which metal is the best reducing agent? a) Mn b) Al c) Ni d) Cr
66 + 68) These two problems are related, and so I will do them together. Note that to find DG°rxn and K (the thermodynamic equilibrium constant) we will use the expression DG°rxn = - nFE°cell lnK = nFE°cell/RT Also recall that (1 C) (1 v) = 1 J a) ox 3 Sn(s) ® 3 Sn2+(aq) + 6 e- E° = + 0.14 v red 2 Fe3+(aq) + 6 e- ® 2 Fe(s) E° = - 0.036 v net 2 Fe3+(aq) + 3 Sn(s) ® 2 Fe(s) + 3 Sn2+(aq) E°net = + 0.104 v n = 6 DG°rxn = - (6) (96485 C/mol) (+ 0.104 v) = - 60.2 kJ/mol ln K = (6) (96485 C/mol) (+ 0.104 v) = 24.28 K = e 24.28 = 3.5 x 1010 (8.314 J/mol.K) (298.2 K) b) ox 2 Cu(s) ® 2 Cu2+(aq) + 4 e- E° = - 0.34 v red O2(g) + 2 H2O(l) + 4 e- ® 4 OH-(aq) E° = + 0.40 v net O2(g) + 2 H2O(l) + 2 Cu(s) ® 4 OH-(aq) + 2 Cu2+(aq) E°net = + 0.06 v n = 4 DG°rxn = - (4) (96485 C/mol) (+ 0.06 v) = - 23.2 kJ/mol ln K = (4) (96485 C/mol) (+ 0.06 v) = 9.34 K = e 9.34 = 1.1 x 104 (8.314 J/mol.K) (298.2 K) c) ox 2 I-(aq) ® I2(s) + 2 e- E° = - 0.54 v red Br2(l) + 2 e- ® 2 Br-(aq) E° = + 1.09 v net Br2(l) + 2 I-(aq) ® 2 Br-(aq) + I2(s) E°net = + 0.55 v n = 2 DG°rxn = = - (2) (96485 C/mol) (+ 0.55 v) = - 106.1 kJ/mol ln K = (2) (96485 C/mol) (+ 0.55 v) = 42.81 K = e42.81 = 3.9 x 1018 (8.314 J/mol.K) (298.2 K)
66 + 68) Use tabulated electrode potentials to calculate DG°rxn for each reaction at 25. °C. Then calculate the equilibrium constant for each reaction. a) 2 Fe3+(aq) + 3 Sn(s) ® 2 Fe(s) + 3 Sn2+(aq) b) O2(g) + 2 H2O(l) + 2 Cu(s) ® 4 OH-(aq) + 2 Cu2+(aq) c) Br2(l) + 2 I-(aq) ® 2Br-(aq) + I2(s)
7) The salt bridge is used to complete the circuit. It provides a way in which charge can pass from one part of the cell to the other part without having the two parts of the cell directly react chemically.
7) Explain the purpose of a salt bridge in an electrochemical cell.
1054 J
A Btu equals _______ J
cathode ray tube
A Piece of Equipment used by Thomson to discover the electron.
1.6 x 10-19 coulombs
A charge of 1 e is equal
anhydrous
A compound in which all water has been removed, usually by heating.
state function
A function that depends only on the initial and final states of a system, not on the path in between
a. 80.2 J. b. 19.2 cal
A good pitcher can throw a baseball so that it travels between 60 and 90 miles per hour (although speeds in excess of 100 miles per hour have been recorded). A regulation baseball weighing 143 g (0.143 kg) travels 75 miles per hour (33.5 m/s). What is the kinetic energy of this baseball in joules? in calories?
polymer
A long molecule consisting of many similar or identical monomers linked together.
combustion analysis
A method used to determine the composition of compounds containing the elements carbon, hydrogen, and occasionally nitrogen.
collision model
A model of reactioin rates based on the idea that molecules must collide to react; it explains the factores influencing reaction rates in terms of frequency of collisions, the number of collisions with energies exceeding the activation energy, and the probability that the collisions occur with suitable orientations.
anion
A negatively charged ion.
quantum number
A number that specifies certain properties of electrons, n
atomic symbol
A one or two letter symbol indicating a particular element.
endothermic reaction
A reaction in which energy is absorbed
gas evolution reaction
A reaction in which two aqueous solutions are mixed and a gas is forms, resulting in bubbling.
-1.36 x 10^3 kJ
A sample of ethanol, C2H5OH, weighing 2.84 g was burned in an excess of oxygen in a bomb calorimeter. The temperature of the calorimeter rose from 25.00C to 33.73C. If the heat capacity of the calorimeter and contents was 9.63 kJ/C, what is the value of q for burning 1 mol of ethanol at constant volume and 25.00C? The reaction is C2H5OH(l) + 3O2(g) = 2CO2(g) + 3H2O(l)
decanting
A separation method that involves pouring off the liquid
nonelectrolyte
A substance that dissolves in water to give a solution that does not conduct an electric current
structural formula
A type of molecular notation in which the constituent atoms are joined by lines representing covalent bonds.
joule
A unit of work equal to one Newton-meter.
heat
About 80% of the energy we need is for _______ The rest is used for muscular action, chemical processes, and other body processes
millions of years ago when aquatic plants and animals were buried and compressed by layers of sediment at the bottoms of swamps and seas.
All of the fossil fuels in existence today were created
1s² 2s² 2p⁶ 3s² 3p¹
Aluminum (Al)
-666 kj
Ammonia burns in the presence of a copper catalyst to form nitrogen gas. 4NH3(g) + 3O2(g) = 2N2(g) + 6H2O(g); H -1267 kJ What is the enthalpy change to burn 35.8 g of ammonia?
NaHCO3(aq) + HCl(aq) > NaCl(aq) + H2O(l ) + CO2(g); Change in H = + 12.7 kJ
Aqueous sodium hydrogen carbonate solution (baking soda solution) reacts with hydrochloric acid to produce aqueous sodium chloride, water, and carbon dioxide gas. The reaction absorbs 12.7 kJ of heat at constant pressure for each mole of sodium hydrogen carbonate. Write the thermochemical equation for the reaction
arsenite
AsO₃⁻³
arsenate
AsO₄⁻³
Since the atomic ratio of nitrogen to hydrogen is 1:3, divide the mass of N by one-third of the mass of hydrogen to find the relative mass of N. = 13.90
Atomic Masses Ammonia is a gas with a characteristic pungent odor. It is sold as a water solution for use in household cleaning. The gas is a compound of nitrogen and hydrogen in the atomic ratio 1 : 3. A sample of ammonia contains 7.933 g N and 1.712 g H. What is the atomic mass of N relative to H?
borate
BO₃⁻³
perborate
BO₄⁻³
1s² 2s²
Beryllium (Be)
1s² 2s² 2p¹
Boron (B)
hypobromite
BrO⁻¹
bromite
BrO₂⁻¹
bromate
BrO₃⁻¹
perbromate
BrO₄⁻¹
cyanide
CN⁻¹
carbonate
CO₃⁻²
calcium sulfate hemihydrate
CaSO4•½H2O ; plaster of Paris
q =4.18 J/(gC) x 15.0 g x (30.0C) = 1.88 x 10^3 J
Calculate the heat absorbed by 15.0 g of water to raise its temperature from 20.0C to 50.0C (at constant pressure). The specific heat of water is 4.18 J/(gC).
stiochiometry
Calculation of the quantities of reactants and products in a chemical reaction
(a) physical (b) physical (c) chemical (d) physical e. chemical f. physical g. chemical h. chemical
Chemical and Physical Changes; Properties of Substances Which of the following are physical changes and which are chemical changes? a. melting of sodium chloride b. pulverizing of rock salt c. burning of sulfur d. dissolving of salt in water e. spoiling of food f. mixing lemonade powder into water g. corroding h.. frying an egg
5.24 x 10^ -21 J/molecule
Chlorine dioxide, ClO2, is a reddish yellow gas used in bleaching paper pulp. The average speed of a ClO2 molecule at 25C is 306 m/s. What is the kinetic energy (in joules) of a ClO2 molecule moving at this speed?
the empirical formula is Na2Cr2O7
Chromium forms compounds of various colors. (The word chromium comes from the Greek khroma, meaning "color"; see Figure 3.9.) Sodium dichromate is the most important commercial chromium compound, from which many other chromium compounds are manufactured. It is a bright orange, crystalline substance. An analysis of sodium dichromate gives the following mass percentages: 17.5% Na, 39.7% Cr, and 42.8% O. What is the empirical formula of this compound? (Sodium dichromate is ionic, so it has no molecular formula.)
hypochlorite
ClO⁻¹
chlorite
ClO₂⁻¹
chlorate
ClO₃⁻¹
perchlorate
ClO₃⁻¹
CoSO4•7H2O(s) → CoSO4•H2O(s) + 6H2O(g) [3.548 g] = [2.184 g + (3.548 - 2.184 = 1.364 g)] Mass of one H2O per 3.548 g of CoSO4•7H2O = 1.364 g ÷ 6 = 0.22733 g Mass of anhydrous CoSO4 = 2.184 g CoSO4•H2O - 0.22733 g H2O = 1.9566 g = 1.957 g
Cobalt(II) sulfate heptahydrate has pink-colored crystals.When heated carefully, it produces cobalt(II) sulfate monohydrate,which has red crystals. What are the formulas of these hydrates? If 3.548 g of the heptahydrate yields 2.184 g of the monohydrate, how many grams of the anhydrous cobalt(II) sulfate could be obtained?
-1.9 kj/g
Colorless nitric oxide, NO, combines with oxygen to form nitrogen dioxide, NO2, a brown gas. 2NO(g) + O2(g) = 2NO2(g); H -114 kJ What is the enthalpy change per gram of nitric oxide?
29.8 g
Conservation of Mass Zinc metal reacts with yellow crystals of sulfur in a fiery reaction to produce a white powder of zinc sulfide. A chemist determines that 65.4 g of zinc reacts with 32.1 g of sulfur. How many grams of zinc sulfide could be produced from 20.0 g of zinc metal?
chromite
CrO₃⁻²
chromate
CrO₄⁻²
Take the diameter of which is 1.86Å x 2 Convert that to miles Then multiply it by the number of atoms lined up. = 6.06 x 10^9 miles
Cumulative-Skills Problems There are 2.619 x 10^22 atoms in 1.000 g of sodium. Assume that sodium atoms are spheres of radius 1.86 Å and that they are lined up side by side. How many miles in length is the line of sodium atoms?
oxalate
C₂O₄⁻²
high precision low accuracy
Determine precision and accuracy
m = 9.11 x 10⁻³¹ kg e = -1.6 x 10⁻¹⁹ C
Electron ;write the charge, the mass
5.5 x 10-1
Electron Mass (amu)
Cl-35: 17 protons, 18 neutrons, 17 electrons
Electrons, Protons, and Neutrons Naturally occurring chlorine is a mixture of the isotopes Cl-35 and Cl-37. How many protons and how many neutrons are there in each isotope? How many electrons are there in the neutral atoms?
28/14Si
Electrons, Protons, and Neutrons What is the nuclide symbol for the nucleus that contains 14 protons and 14 neutrons?
group
Elements in the same vertical column of the periodic table; also called a family
hydrogen sulfate
HSO₄⁻¹
(a) solution (b) substance (c) substance (d) heterogeneous mixture
Elements, Compounds, and Mixtures Label each of the following as a substance, a heterogeneous mixture, or a solution. a. seawater b. sulfur c. fluorine d. beach sand
(a) pure substance; bromine liquid, bromine gas (b) mixture; liquid solution and solid (c) pure substance; nonmolten portion (solid), liquid (d) mixture; solid sodium hydrogen carbonate and solid potassium hydrogen tartrate
Elements, Compounds, and Mixtures Which of the following are pure substances and which are mixtures? For each, list all of the different phases present. a. bromine liquid and its vapor b. paint, containing a liquid solution and a dispersed solid pigment c. partially molten iron d. baking powder containing sodium hydrogen carbonate and potassium hydrogen tartrate
antifreeze
Ethylene Glycol, A chemical that is mixed with water and added to the cooling system of a car. It moves through the engine to remove extra heat.
rate law
Experimentally determined mathematical expression showing the rate of a reaction as a function of the concentration of its reactants.
Pressure
Force/Area or N/ m^2
C 40 percent H 6.73 percent O 53.3 percent
Formaldehyde, CH2O, is a toxic gas with a pungent odor. Large quantities are consumed in the manufacture of plastics (Figure 3.5), and a water solution of the compound is used to preserve biological specimens. Calculate the mass percentages of the elements in formaldehyde (give answers to three significant figures).
5.81 x 10^-3 mol CaSO4 1.16 x 10^-2 mol H2O
Formula Masses and Mole Calculations Calcium sulfate, CaSO4, is a white, crystalline powder. Gypsum is a mineral, or natural substance, that is a hydrate of calcium sulfate. A 1.000-g sample of gypsum contains 0.791 g CaSO4. How many moles of CaSO4 are there in this sample? Assuming that the rest of the sample is water, how many moles of H2O are there in the sample? Show that the result is consistent with the formula CaSO42H2O.
a. Formula weight of CH3OH = AW of C + 4(AW of H) + AW of O. Using the values of atomic weights in the periodic table (inside front cover) rounded to four significant figures and rounding the answer to three significant figures, we have FW = 12.01 amu + (4 x 1.008 amu) + 16.00 amu = 32.042 = 32.0 amu b. FW of NO3 = AW of N + 3(AW of O) = 14.01 amu + (3 x 16.00 amu) = 62.01 = 62.0 amu c. FW of K2CO3 = 2(AW of K) + AW of C + 3(AW of O) = (2 x 39.10 amu) + 12.01 amu + (3 x 16.00 amu) = 138.210 = 138 amu d. FW of Ni3(PO4)2 = 3(AW of Ni) + 2(AW of P) + 8(AW of O) = (3 x 58.70 amu) + (2 x 30.97 amu) + (8 x 16.00 amu) = 366.040 = 366 amu
Formula Masses and Mole Calculations Find the formula masses of the following substances to three significant figures. a. methanol, CH3OH b. nitrogen trioxide, NO3 c. potassium carbonate, K2CO3 d. nickel phosphate, Ni3(PO4)2
First, find the formula weight of NH4NO3 by adding the respective atomic weights. Then convert it to the molar mass: FW of NH4NO3 = 2(AW of N) + 4(AW of H) + 3(AW of O) = (2 x 14.01 amu) + (4 x 1.008 amu) + (3 x 16.00 amu) = 80.052 amu The molar mass of NH4NO3 = 80.05 g/mol.
Formula Masses and Mole Calculations Ammonium nitrate, NH4NO3, is used as a nitrogen fertilizer and in explosives. What is the molar mass of NH4NO3?
Btu's (British thermal units) per pound, which are essentially heats of combustion per pound of coal
Fuel values of coals are rated in
redox reaction
Gain of electrons, an oxidation reaction paired with a reduction reaction
(atoms of hydrogen given)(molecules of ethanol)/ (atoms of hydrogen per ethanol) =7.0 x 10^22 C2H5OH molecules
General Problems A sample of ethanol (ethyl alcohol), C2H5OH, contains 4.2 x10^23 hydrogen atoms. How many C2H5OH molecules are in this sample?
Let: x = number of protons. Then 1.21x is the number of neutrons. Since the mass number is 62, you get 62 = x + 1.21 x = 2.21 x Thus, x = 28.054, or 28. The element is nickel (Ni). Since the ion has a +2 charge, there are 26 electrons.
General Problems A monatomic ion has a charge of +2. The nucleus of the ion has a mass number of 62. The number of neutrons in the nucleus is 1.21 times that of the number of protons. How many electrons are in the ion? What is the name of the element?
Trick question, since there are 4.30 x 10^22 HNO3 molecules and one nitrogen molecule in a molecule of HNO3, then there is 4.30 x 10^22 HNO3 N atoms in that many molecules. Part 2 (2.81 g HNO3)(4.30 x 10^22 HNO3) /(4.50 g) (molecules of HNO3)(3 atoms of O) /(1 molecule of HNO3) = 8.06 x 10^22 O atoms
General Problems Nitric acid is composed of HNO3 molecules. A sample weighing 4.50 g contains 4.30 x 10^22 HNO3 molecules. How many nitrogen atoms are in this sample? How many oxygen atoms are in 2.81 g of nitric acid?
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p²
Germanium (Ge)
Solutions: 1. In sodium fluoride, there is one atom of sodium and one atom of fluorine. The molar mass will then be: (1 atom x 23 grams/mole of sodium) + (1 atom x 19 grams/mole of fluorine) = 42 grams/mole of sodium fluoride 2. In potassium hydroxide, there is one atom of potassium, one atom of hydrogen, and one atom of oxygen. The molar mass will then be (1 x 39 grams) + (1 x 1 gram) + (1 x 16 grams) = 56 grams/mole of potassium hydroxide 3. In copper (I) chloride, there is one atom of copper and one atom of chlorine. The molar mass is then (1 x 63.5 grams) + (1 x 35.5 grams) = 99 grams/mole of copper (I) chloride 4. In manganese (IV) oxide, there is one atom of manganese and two atoms of oxygen. The molar mass is then (1 x 55 grams) + (2 x 16 grams) = 87 grams/mole of manganese (IV) oxide 5. In calcium sulfate, there is one atom of calcium, one atom of sulfur, and four atoms of oxygen. The molar mass is then (1 x 40 grams) + (1 x 32 grams) + (4 x 16 grams) = 136 grams/mole of calcium sulfate 6. In magnesium phosphate, there are three atoms of magnesium, two atoms of phosphorus, and eight atoms of oxygen. (The formula is Mg3(PO4)2). The molar mass is then (3 x 24 grams) + (2 x 31 grams) + (8 x 16 grams) = 262 grams/mole of magnesium phosphate
Give the molar masses of the following compounds: 1. sodium fluoride 2. potassium hydroxide 3. copper (I) chloride 4. manganese (IV) oxide 5. calcium sulfate 6. magnesium phosphate
hydrogen carbonate
HCO₃⁻¹
hydrogen oxalate/binoxalate
HC₂O₄⁻¹
monohydrogen phosphate
HPO₄⁻²
hydrogen sulfite
HSO₃⁻¹
698 g Fe
Hematite, Fe2O3, is an important ore of iron; see Figure 3.12. (An ore is a natural substance from which the metal can be profitably obtained.) The free metal is obtained by reacting hematite with carbon monoxide, CO, in a blast furnace. Carbon monoxide is formed in the furnace by partial combustion of carbon. The reaction is Fe2O3(s) + 3CO(g) ---> 2Fe(s) + 3CO2(g) How many grams of iron can be produced from 1.00 kg Fe2O3?
33.4 g
How many grams of carbon are there in 83.5 g of formaldehyde, CH2O? Use the percentage composition obtained in the previous example (40.0% C, 6.73% H, 53.3% O).
35
How many hydrogen atoms are in 5 molecules of isopropyl alchohol, C3H7O?
5.71 x10^22 HCl molecules
How many molecules are there in a 3.46-g sample of hydrogen chloride, HCl?
Thus, 2.45 x 106 kJ of heat evolves
How much heat is evolved when 9.07 x 10^5 g of ammonia is produced according to the following equation? (Assume that the reaction occurs at constant pressure.) N2(g) + 3H2(g) > 2NH3(g); ΔH = 91.8 kJ
50.6 kJ
Hydrazine, N2H4, is a colorless liquid used as a rocket fuel. What is the enthalpy change for the process in which hydrazine is formed from its elements? N2(g) + 2H2(g) = N2H4(l ) Use the following reactions and enthalpy changes: N2H4(l ) + O2(g) = N2(g) + 2H2O(l ); H -622.2 kJ H2(g) + 1/2O2(g) = H2O(l ); H -285.8 kJ
HBr
Hydrobromic acid
1s¹
Hydrogen (H)
HI
Hydroiodic Acid
hydrogen
H⁺¹
Carbonic acid
H₂CO₃
dihydrogen phosphate
H₂PO₄⁻¹
hypoiodite
IO⁻¹
iodite
IO₂⁻¹
iodate
IO₃⁻¹
periodate
IO₄⁻¹
101g/mol
If the density of an unknown gas Z is 4.50g/L at STP, what is the molar mass of gas Z?
C2H4O2
In Example 3.9, we found the percentage composition of acetic acid to be 39.9% C, 6.7% H, and 53.4% O. Determine the empirical formula. The molecular mass of acetic acid was determined by experiment to be 60.0 amu. What is its molecular formula?
2.7 g O2
In a process for producing acetic acid, oxygen gas is bubbled into acetaldehyde, CH3CHO, containing manganese(II) acetate (catalyst) under pressure at 60C. 2CH3CHO(l) + O2(g) ----> 2HC2H3O2(l) In a laboratory test of this reaction, 20.0 g CH3CHO and 10.0 g O2 were put into a reaction vessel. a. How many grams of acetic acid can be produced by this reaction from these amounts of reactants? b. How many grams of the excess reactant remain after the reaction is complete?
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶
Krypton (Kr)
0.141 mol PbCrO4
Lead(II) chromate, PbCrO4, is a yellow paint pigment (called chrome yellow) prepared by a precipitation reaction (Figure 3.4). In a preparation, 45.6 g of lead(II) chromate is obtained as a precipitate. How many moles of PbCrO4 is this?
...
Limiting Reactant; Theoretical and Percentage Yields Potassium superoxide, KO2, is used in rebreathing gas masks to generate oxygen. 4KO2(s) + 2H2O(l ) ---> 4KOH(s) + 3O2(g) If a reaction vessel contains 0.25 mol KO2 and 0.15 mol H2O, what is the limiting reactant? How many moles of oxygen can be produced?
...
Limiting reagent and yield questions
.14 x 4.15 kg= 0.581 kg N
Mass Percentage A fertilizer is advertised as containing 14.0% nitrogen (by mass). How much nitrogen is there in 4.15 kg of fertilizer?
Mass percentage carbon = ( sample of mass/sample in C of mass) x 100 = 86.27%
Mass Percentage A 1.836-g sample of coal contains 1.584 g C. Calculate the mass percentage of C in the coal.
Start by calculating the moles of Os and O; then divide each by the smaller number of moles to obtain integers for the empirical formula. Mol Os = 2.16 g Os x 1 mol Os/190.2 g Os =0.01136 mol (smaller number) Mol O =0.0456 mol Integer for Os = 0.01136 ÷ 0.01136 = 1.000 Integer for O = 0.0456 ÷ 0.01136 = 4.01 Within experimental error, the empirical formula is OsO4
Mass Percentage An oxide of osmium (symbol Os) is a pale yellow solid. If 2.89 g of the compound contains 2.16 g of osmium, what is its empirical formula?
In each part, the numerator consists of the mass of the element in one mole of the compound; the denominator is the mass of one mole of the compound. Use the atomic weights of C = 12.01 g/mol; O = 16.00 g/mol; Na = 22.99 g/mol; H = 1.008 g/mol; P = 30.97 g/mol; Co = 58.93 g/mol; and N = 14.01 g/mol. Percent C = (C of mass/CO of mass) x = 42.9% Percent O = 100.000% - 42.878%C = 57.122 = 57.1%
Mass Percentage Calculate the percentage composition for each of the following compounds (three significant figures). a. CO
Mol K =1.013 mol÷ 0.5078 =2 Mol Mn =0.5078 mol (smallest number)÷ 0.5078 =1 Mol O =2.031 mol÷ 0.5078 =4 K2MnO4.
Mass Percentage Potassium manganate is a dark green, crystalline substance whose composition is 39.6% K, 27.9% Mn, and 32.5% O, by mass. What is its empirical formula?
The formula weight corresponding to the empirical formula C2H6N may be found by adding the respective atomic weights. Formula weight = 44.08 amu 88.5 amu ÷ 44.1 amu = 2.006, or 2 Therefore, the molecular formula is (C2H6N)2, or C4H12N2.
Mass Percentage Putrescine, a substance produced by decaying animals, has the empirical formula C2H6N. Several determinations of molecular mass give values in the range of 87 to 90 amu. Find the molecular formula of putrescine
ethanol
Mass Percentage Which contains more carbon, 6.01 g of glucose, C6H12O6, or 5.85 g of ethanol, C2H6O?
manganate
MnO₃⁻¹
permanganate
MnO₄⁻¹
...
Molarity skills
4.10 x 10^22 N atoms, 2.73 x 10^22 N atoms
Molecular and Ionic Substances A 1.50-g sample of nitrous oxide (an anesthetic, sometimes called laughing gas) contains 2.05 x 10^22 N2O molecules. How many nitrogen atoms are in this sample? How many nitrogen atoms are in 1.00 g of nitrous oxide?
1 Fe to 6 O
Molecular and Ionic Substances Iron(II) nitrate has the formula Fe(NO3)2. What is the ratio of iron atoms to oxygen atoms in this compound?
Fe(CN)3 b. K2SO4 c. Li3N d. Ca3P2
Molecular and Ionic Substances Write the formula for the compound of each of the following pairs of ions. a. Fe3 and CN b. K and (SO4)2 c. Li and N3 d. Ca2 and P3
orientation factor
Molecules must also be oriented in a certain way for the collision to lead to a reaction., not all collisions will yield a reaction,
nitrite
NO₂⁻¹
nitrate
NO₃⁻¹
LiOH NaOH KOH Ca(OH)2 Sr(OH)2 Ba(OH)2
Name all strong bases
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁸
Nickel (Ni)
cyanate
OCN⁻¹
hydroxide
OH⁻¹
10-10 m
One angstrom is
1s² 2s² 2p⁴
Oxygen (O)
peroxide
O₂⁻²
phosphite
PO₃⁻³
phosphate
PO₄⁻³
HBrO4
Perbromic Acid
a. C: Group IVA, Period 2; nonmetal b. Po: Group VIA, Period 6; metal c. Cr: Group VIB, Period 4; metal d. Mg: Group IIA, Period 3; metal e. B: Group IIIA, Period 2; metalloid
Periodic Table Identify the group and period for each of the following. Refer to the periodic table (Figure 2.15 or inside front cover). Label each as a metal, nonmetal, or metalloid. a. C b. Po c. Cr d. Mg e. B
E = hν h = 6.6 x 10⁻³⁴J-s
Planck's formula
1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹
Potassium (K)
(a) K (b) S (c) Fe (d) Mn
Practice Problems Give the atomic symbol for each of the following elements. a. potassium b. sulfur c. iron d. manganese
(a) argon (b) zinc (c) silver (d) magnesium
Practice Problems What is the name of the element represented by each of the following atomic symbols? a. Ar b. Zn c. Ag d. Mg
7.96 gram
Propane, C3H8, is a common fuel gas. Use the following to calculate the grams of propane you would need to provide 369 kJ of heat. C3H8(g) + 5O2(g) = 3CO2(g) + 4H2O(g); H 2043 kJ
complementary properties
Properties that exclude one another - the more you know about one, the less you know about the other., wave nature and particle nature of the electron
1.0073
Proton Mass (amu)
m = 1.67 x 10⁻²⁷ kg e = +1.6 x 10⁻¹⁹ C
Proton;write the charge, the mass
HClO4 H2SO4 HI HBr HCl HNO3
Recognizing strong and weak acids Name all strong acids
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s¹
Rubidium (Rb)
sulfite
SO₃⁻²
sulfate
SO₄⁻²
observation hypothesis- which should be falsified experiment Law or theory
Scientific Approach List Them
silicate
SiO₄⁻⁴
(a) 6 (b) 3 (c) 4 (d) 5 (e) 3 (f) 4
Significant Figures How many significant figures are there in each of the following measurements? a. 73.0000 g b. 0.0503 kg c. 6.300 cm d. 0.80090 m e. 5.10 x 10^-7 m f. 2.010 s
(a) 8.5 (b) 92.9 (c) 111 (d) 2.3 x 10^3
Significant Figures a. (8.71 x 0.0301)/ (.031) b. 0.71 + 92.2 c. 934 x 0.00435 + 107 d. (847.89 - 847.73) x 14673
1s² 2s² 2p⁶ 3s² 3p²
Silicon (Si)
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Stiochemistry Reaction Skills
By inspecting the balanced equation, obtain a conversion factor of eight mol CO2 to two mol C4H10. Multiply the given amount of 0.30 moles of C4H10 by the conversion factor to obtain the moles of H2O. 1.2 mol CO2
Stoichiometry: Quantitative Relations in Reactions Butane, C4H10, burns with the oxygen in air to give carbon dioxide and water. 2C4H10(g) + 13O2(g) --> 8CO2(g) + 10H2O(g) What is the amount (in moles) of carbon dioxide produced from 0.30 mol C4H10?
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s²
Strontium (Sr)
1s² 2s² 2p⁶ 3s² 3p⁴
Sulfur (S)
Arrhenius
Swedish chemist who developed a formula for the temperature dependence of the rate constant in a chemical reaction
(a) 20C (b) -31C (c) 79F (d) -94F
Temperature Conversion Convert: a. 68F to degrees Celsius b. -23F to degrees Celsius c. 26C to degrees Fahrenheit d. -70C to degrees Fahrenheit
C= (F-32F)/1.8
Temperature equation for Celsius to Fahrenheit: What is it?
joule
The SI unit of energy, kg x m2/s2 is given the name
enthalpy of reaction
The amount of energy released or absorbed as heat during a chemical reaction.
electron configuration
The arrangement of electrons in the orbitals of an atom.
space filling model
a model of a molecule showing the relative sizes of the atoms and their relative orientations
positive; cold
The process of dissolving ammonium nitrate, NH4NO3, in water is an endothermic process. What is the sign of q? If you were to add some ammonium nitrate to water in a flask, would you expect the flask to feel warm or cool?
thermodynamic system
The substance or mixture of substances under study in which a change occurs is called the
formula mass
The sum of the atomic masses of all the atoms in a chemical formula
molar volume
The volume occupied by a mole of any gas at STP
atomic element
Those elements that exist in nature with single atoms as their basic units.
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d²
Titanium (Ti)
hyperventilate
To provide ventilations at a higher rate than normal.
8.40 g HCl
Today chlorine is prepared from sodium chloride by electrochemical decomposition. Formerly chlorine was produced by heating hydrochloric acid with pyrolusite (manganese dioxide, MnO2), a common manganese ore. Small amounts of chlorine may be prepared in the laboratory by the same reaction (see Figure 3.13): 4HCl(aq) + MnO2(s) ----> 2H2O(l) + MnCl2(aq) + Cl2(g) How many grams of HCl react with 5.00 g of manganese dioxide, according to this equation?
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Using knowledge of strong acid and base
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d³
Vanadium (V)
crystalline
Very orderly arrangement
λν = V λ = wavelength in m ν = frequency in Hz = cycles/sec V = velocity in m/s
Wavelength, velocity and frequency of a wave;write the equation
ΔH° = Σ n ΔH°(final) - ΔH° = Σ n ΔH°(initial) : m and n are the coefficients of the substances in the chemical equation
What is the change of standard enthalpy of reaction equation?
ΔH = 40.5 kJ
What is the enthalpy of reaction, H, for the formation of tungsten carbide, WC, from the elements? (Tungsten carbide is very hard and is used to make cutting tools and rock drills.) W(s) + C(graphite) ---> WC(s) The enthalpy change for this reaction is difficult to measure directly, because the reaction occurs at 1400C. However, the heats of combustion of the elements and of tungsten carbide can be measured easily: 1. 2W(s) + 3O2(g) ---> 2WO3(s); H -1685.8 kJ 2. C(graphite) + O2(g) ---> CO2(g); H -393.5 kJ 3. 2WC(s) + 5O2(g) ---> 2WO3(s) + 2CO2(g); H -2391.8 kJ
0.430 mol
What is the number of moles in 9.63L of H2S gas at STP?
Fe(s) + 2HCl(aq) = FeCl2(aq) = H2(g); H -89.1 kJ
When 1 mol of iron metal reacts with hydrochloric acid at constant temperature and pressure to produce hydrogen gas and aqueous iron(II) chloride, 89.1 kJ of heat evolves. Write a thermochemical equation for this reaction.
20.5 kJ
When 15.3 g of sodium nitrate, NaNO3, was dissolved in water in a calorimeter, the temperature fell from 25.00C to 21.56C. If the heat capacity of the solution and the calorimeter is 1071 J/C, what is the enthalpy change when 1 mol of sodium nitrate dissolves in water? The solution process is NaNO3(s) = Na(aq) + NO3 (aq); H = ?
...-385 KJ
When steam condenses to liquid water, 2.26 kJ of heat is released per gram. The heat from 168 g of steam is used to heat a room containing 6.44 104 g of air (20 ft 12 ft 8 ft). The specific heat of air at normal pressure is 1.015 J (gC). What is the change in air temperature, assuming the heat from the steam is all absorbed by air?
5.8 x 10^4 J
You wish to heat water to make coffee. How much heat (in joules) must be used to raise the temperature of 0.180 kg of tap water (enough for one cup of coffee) from 19C to 96C (near the ideal brewing temperature)? Assume the specific heat is that of pure water, 4.18 J /(gC).
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹
Yttrium (Y)
20.9 g ZnI2
Zinc iodide, ZnI2, can be prepared by the direct combination of elements (Figure 3.3). A chemist determines from the amounts of elements that 0.0654 mol ZnI2 can form. How many grams of zinc iodide is this?
0.26 mol
Zinc metal reacts with hydrochloric acid by the following reaction: Zn(s) + 2HCl(aq) ----> ZnCl2(aq) + H2(g) If 0.30 mol Zn is added to hydrochloric acid containing 0.52 mol HCl, how many moles of H2 are produced?
3, 2, 2, 3
__Al + __Cu(NO₃)₂ --> __Cu + __Al(NO₃)₃
1, 3, 2, 3
__Al₂(SO₄)₃ + __Ca(OH)₂ --> __Al(OH)₃ + __CaSO₄
balanced
__C + __O₂ --> __CO₂
balanced
__CaO + __H₂O --> __Ca(OH)₂
2, 1, 2
__H₂ + __O₂ -->__H₂O
2, 1, 2
__K + __I₂ --> __KI
carbonic acid
a compound with the formula H2CO3 that results from the combination of carbon dioxide (CO2) and water (H2O); of particular importance in maintaining the body's acid-base balance.
bomb calorimeter
a device used to determine the energy content of food by combustion and calculation of water temperature change to indicate heat (energy) release
second order
a doubling of the initial concentration equals a doubling of the rate
empirical formula
a formula showing the lowest whole number ratio of atoms in a compound
The burning of sulfur-containing coal
a major source of air pollution and acid rain
entropy
a measure of the disorder of a system, Chaos or randomness of a system, usually denoted as S. ΔS represents the change in _________ following a reaction.
calorimeter
a measuring instrument that determines quantities of heat
heisenberg uncertainty
cannot find the precise position of the electron, only approximate, It is impossible to know exactly both the velocity and the position of a particle at the same time
H2CO3
carbonic acid
sublination
change of state from solid to gas., water is converted from a solid to a gas
empirical (simplest) formula
chemical formula that shows the kinds of atoms and their relative numbers in a substance in the smallest possible whole-nimber ratios
HClO3
chloric acid
HClO2
chlorous acid
H2CrO4
chromic acid
SI derived unit
combinations of SI base units
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combustion reaction
inorganic compound
compound that does not contain carbon
robert millikan
determined the mass of an electron, 1909 oil drop experiment, calculated the charge of the electron, calculate the mass of electrons
calorimeter
device used to measure the heat absorbed or evolved during a physical or chemical change
...
draw the ideal gas constant
aufbau principal
electrons occupy the orbitals of lowest energy first
substance
element or compound that cannot be broken down into simpler components and maintain the properties of the original substance
law of conservation of energy
energy may be converted from one form to another, but the total quantity of energy remains constant
kinetic energy
energy of motion
potential energy
energy stored due to an object's position or arrangement
random error
error that equals itself out, all measurement have this error
systematic error
error that is too high or too low doesn't average itself out
infinite number of significant figures
exact numbers have how many significant figures
amorphous
formless; lacking shape or definition
ernest rutherford
from his gold foil expirments, he knew some substances give off + charged particles called alpha particles, most of the mass of an atom is in the nucleus, he reasoned that electrons in the atom are whirled around outside the nucleus, most of the atom is empty space
...
gas evolution problems
degenerate orbital
group of orbitals within the same energy level
crystalline
having particles arranged in repeating geometric patterns
q = CΔt
heat capacity equation is
enthalpy
heat content of a system at constant pressure, H, A measurement of the energy content of a system.
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highlight the exception to electronconfiguration
period
horizontal row in the periodic table
precision
how close a series of measurements are to one another
towards the lowest enthalpy
how does a chemical system proceed it term of potential energy
it proceeds to the lowest potential energy
how does a mechanical system proceed it term of potential energy
HCL
hydrochloric acid
HF
hydrofluoric acid
HCN
hydrogen cyanide
hydronium ion
hydrogen ion combines with a water molecule to form a XXXXXXXXX, H3O(+)
H2O2
hydrogen peroxide
H2S
hydrogen sulfate
zero order or second order
if half life is dependent on initial reaction it is
first order reaction
if half life is independent of initial concentration it is
first order reaction
if the rate doubles it is a
pure water is a nonconductor of electricity
if the water were truly pure, the person would be safe from electrocution, because
net ionic equation:
includes only those compounds and ions that undergo a chemical change in a reaction in an aqueous solution
HIO3
iodic acid
monatomic ion
ion formed from a single atom
hydrated ionic compounds
ionic compounds containing a precise number of water molecules. use Greek prefixes for the number of molecules
endothermic process
is a chemical reaction or a physical change in which heat is absorbed (q is positive).
exothermic process
is a chemical reaction or a physical change in which heat is evolved (q is negative);
enthalpy
is a measure of the total energy of a thermodynamic system
calorie (cal)
is a non-SI unit of energy commonly used by chemists, originally defined as the amount of energy required to raise the temperature of one gram of water by one degree Celsius
standard enthalpy of formation
is the enthalpy change for the formation of one mole of the substance in its standard state from its elements in their reference form and in their standard states
heat of reaction
is the value of q required to return a system to the given temperature at the completion of the reaction
joseph proust
law of definate composition, developed the Law of Definite Proportions
mixture
material composed of two or more elements or compounds that are physically mixed together but not chemically combined
Pauli exclusion
maximum of 2 electrons may occupy a single atomic orbital, but only if the electrons have opposite spins
CH4
methane
organic compound
most compounds that contain carbon
quantum numbers
n, l, ml, ms, The four numbers that define each particular electron of an atom. The Principle Quantum Number (n) describes the electrons' energy and distance from the nucleus. The Angular Momentum Quantum Number (l) describes the shape of the orbital in which the electron resides. The Magnetic Quantum Number (m describes the orientation of the orbital in space. The Spin Quantum number describes whether the spin of the electron is positive or negative.
HNO3
nitric acid
HNO2
nitrous acid
pauli exclusion
no two electrons can have the same set of quantum numbers, principle that states that no two electrons can have the same exact set of quantum numbers within one atom
collision frequency
number of collisions between particles per second
atomic number (Z)
number of protons in the nucleus
exact numbers
numbers known with certainty
heat capacity
of a sample of substance is the quantity of heat needed to raise the temperature of the sample of substance one degree Celsius (or one kelvin).
oxidation number
of an atom in a substance as the actual charge of the atom if it exists as a monatomic ion, or a hypothetical charge assigned to the atom in the substance by simple rules
Hess's law of heat summation
or a chemical equation that can be written as the sum of two or more steps, the enthalpy change for the overall equation equals the sum of the enthalpy changes for the individual steps
hydrocarbon
organic molecule composed of only carbon and hydrogen atoms
...
oxidation numbers
henderson haselbach equation
pH = pKa + log ([A-]/[HA]) [A-] concentration of conjugate base [HA] concentration of acid Ka = dissociation constant
HClO4
perchloric acid
HIO4
periodic acid
H3PO4
phosphoric acid
true
popsition of an electron is related to the particle nature
cation
positively charged ion
periodic property
property of elements that is predictable based on it's position in the periodic table
state function
property of the system that changes independently of its pathway
chemical property
relates to a substance's ability to undergo changes that transform it into different substances
ΔH
s called the standard enthalpy of reaction
mendelev
scientist credited with the first periodic table of elements
formula unit
simplest collection of atoms from which an ionic compound's formula can be established
quarks
small particles that make up protons and neutrons
atom
smallest particle of an element
q = smΔt
specific heat capacity equation is
exo
spontaneous reactions are exo or endo
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stiochemistry morality questions
H2SO4
sulfuric acid
H2SO3
sulfurous acid
electrons
surrounding the nucleus at a distance of about 1 to 3 A
mole
the SI base unit used to measure the amount of a substance whose number of particles is the same as the number of atoms of carbon in exactly 12 g of carbon-12
calorie
the amount of heat needed to raise or lower one gram of water one degree C= 4.1845
theoretical yield
the amount of product that can be made in a chemical reaction based on the amount of limiting reactant
Enthalpy
the amount of thermal energy emitted or absorbed by a chemical reaction, under conditions of constant pressure
lattice energy
the energy associated with constructing a crystal lattice relative to the energy of all constituent atoms separated by infinite distances
heat of reaction
the enthalpy change for a chemical equation exactly as it is written
heat capacity
the heat required to raise the temperature of a substance is called its
specific heat
the heat required to raise the temperature of one gram of a substance one degree centigrade
