General Chemistry UWORLD Atoms and molecules

Zeff of Nitrogen?

+7-2 = 5

STP

0 degrees C and atm 1 mol/22.4 liters

Which of the following statement(s) is(are)consistent with the molar mass of ammonium carbonate? 1.00 mol of (NH4)2CO3 contains 96.11 g of mass. 96.11 g of (NH4)2CO3 contains 6.022 × 1023 (NH4)2CO3 molecules. 96.11 amu of (NH4)2CO3 contains 1.00 mol (NH4)2CO3.

1 & 2. 3 is wrong because amu refers to the weight of a single molecule of NH42CO3, which does not contain the same mass as a mole of molecules.

Pressure units

1 atm=760 mmHg=760 torr=101.325 kPa

Molar volume of a gas at STP

1 mol/22.4 L

Suppose 18O nucleus absorbs a proton without ejecting a neutron. The resulting nucleus formed would be an isotope of:

180 + 1X = 19F 9 1 9

18F-FDG positron emission

18F = X + 0e 9 +1 x = 18O 8

Molar volume at STP

22.4 L/mol

The last step in the synthesis of 18F-FDG is a hydrolysis reaction to remove the acetyl (OAc) protecting groups. If 524 mg of acetylated 18F-FDG is hydrolyzed, how many millimoles of the acetyl group are removed in the reaction? (Note: The molar mass of the acetylated 18F-FDG is 349.31 g/mol = 349.31 mg/mmol.)

524mg/349.31mg/mmol = 1.5 mmols x the molar ratio which is 4/1 = 6 mmol.

Zeff of Xenon?

54-46 = 8

What is the mass percent of alcohol in a solution containing 62 mL of ethyl alcohol mixed into 200 mL of water? (Note: Density of ethyl alcohol = 0.8 g/mL; density of water = 1 g/mL.)

62 ml / .8g/ml = 50 g Alcohol 200 ml / 1/ml = 200 g H20 50 g alcohol/250 g = .20 x 100% = 20%.

Gadolinium becomes ionized to Gd3+ when it loses electrons from which orbital(s)? What is the normal e- config and Gd3+ electron config?

6s (2 electrons) and 5d (1 electron) [Xe] 6s25d14f7 [Xe] 4f7

3 H2O + 5 ClO3− + 3 I2 → 5 Cl− + 6 IO3− + 6 H+ Consider the reaction of iodine with ClO3− under acidic conditions, as shown above. If 6 moles of electrons are required to reduce 1 mole of ClO3−, how many moles of electrons are required to completely reduce all the ClO3− ions present in 250 mL of a 4.8 M ClO3− solution?

7.2. Don't forget molar ratio silly

Single Replacement

A + BC --> B + AC A single element reacts with a compound (a substance in its elemental form that is not bonded with other types of atoms) and forms a new compound and a new element as the products.

Gay-Lussac's Law

As temperature increases, pressure increases P1/T1=P2/T2

Galileo Thermometer and temperature

As the temperature of the liquid in the thermometer increases, the density of it will decrease. As the temperature of the liquid in the thermometer decreases, the density will increase. However, the density of the isolated bulb system won't change. So if the temperature decreases, the density of the liquid will increase. Thus, the isolated bulb system which hasn't changed will float cause it has a lower density.

Charles' Law

As volume increases, temperature increases V1/T2=V2/T2 Charles was V/T's ex boyfriend

Why is water a great solvent?

Bent MG, small molecule, and hydrogen has a less EN than oxygen, therefore letting it have interactions with other charged molecules.

What diatomic element exists as a liquid at room temp?

Br2

According to ionization energy trends, which metal out of the Alkali metals is most reactive?

Cesium. It has the lowest ionization energy of the metals. Consequently, less energy is required to remove an electron from its valence shell compared to other metals. Therefore it is the most reactive. Remember lithium is commonly used in batteries wouldn't want them to explode now would we :).

+DeltaH

Endothermic. Heat is absorbed and temperature decreases. Downward slope on a temperature vs time graph. The product is less stable.

The energy of a photon is given by

Ephoton=hc/λ . For a molecule or atom to transition from the ground to an excited state, it must absorb a single photon with energy exactly equal to the energy difference between the two states.

What are the formal charges and oxidation states of the Lewis structure of the ClO− anion?

FC of Cl: 0, Oxidation state: +1 FC of O = -1, Oxidation state of O= -2,

Thermodynamic product on a graph (when two or more products are formed, which one is thermo and kinetic)

For a reaction producing more than one product, The compound with a higher energy transition state that produces the lowest energy (most stable) structure is the thermodynamic product.

Kinetic product on a graph (when two or more products are formed, which one is thermo and kinetic)

For a reaction producing more than one product, the product with the lowest energy transition state will form fastest and is the kinetic product.

Density =

Grams/L Or if given radius, Grams/ (2R)^3

Representative elements are

Groups 1-2, 13-18.

what 7 elements are diatomic?

H2, N2, O2, F2, Cl2, Br2, I2

The acid halides are all strong acids except for

HF. This is because F is the smallest atomic radius and highest electronegativity, making the bond incredibly strong. Therefore it doesn't want to donate its proton.

What diatomic element exists as a solid at room temp?

I2

Iodine reacts with ClO3− under acidic conditions according to the reaction shown below. 5 ClO3− + 3 I2 + 3 H2O → 5 Cl− + 6 IO3− + 6 H+ Does I2 act as the oxidizing agent or reducing agent in the reaction?

I2 acts as the reducing agent because it was oxidized.

What increases the kinetic energy of the molecules in a system which therefore increases reaction rate?

Increased temperature

Galileo thermometer trend

Increasing temperature of liquid, the density will decrease and the isolated object will sink Decreasing temperature, the density will increase and the isolated object will float

Ionization energy and reactivity

Ionization energy is the energy required to remove an electron from an atom. Because of the associated ionization and electron transfer involved in forming ionic bonds, the reactivity of atoms forming ionic compounds increases as the ionization energy decreases.

What is reactivity driven by?

It is driven by the tendency of atoms to gain, lose, or share electrons to achieve a more stable electronic configuration (ie, a full valence shell).

Equilibrium partial pressure

Kp = Products ^ moles/Reactants ^moles

Why does oxygen have the highest EN but the lowest electron affinity compared to other 6A nonmetals?

Oxygen's valence electrons experience more electron-electron repulsion. Electron-electron repulsions result in a decreased electron affinity.

Which of the following accurately describes the magnetic properties of Gd3+ ions?

Paramagnetic because of 7 unpaired electrons in the f orbital. Paramagnetic means

reaction quotient

Ratio of the concentrations of the products to the concentrations of the reactants at any point during the reaction aside from equilibrium, where each reactant and product in the expression is raised to the power of its stoichiometric coefficient. Commonly denoted by Q.

Chemical behavior between atoms is governed largely by what?

Same group aka column. The number of electrons in an atom's valence shell. Atoms in the same group will have similar chemical behavior between them.

Sublimation and deposition

Solid to gas Gas to solid

Bond enthalpy

Sum of bonds broken - Sum of bonds formed Basically add the bond enthalpy reactants up then subtract them from the product.

standard molar enthalpy of formation

The Enthalpy Change when 1 mole of a substance is formed from it's constituent elements under standard conditions. With all reactants and products in their standard states ∆Hc = ∑∆Hf(Products) - ∑∆Hf(Reactants)

What is the molarity of cinoxate (0.250 kg/mol) in 100 mL of sunscreen B16 (density = 1 g/mL)?

The density, percent mass, and molecular weight of a substance can be used to calculate the concentration (molarity) of a solution. The units must be consistent when carrying out these stoichiometric calculations. The density of sunscreen B16 is 1 g/mL, so 100 mL of sunscreen will have a mass of 1 g/mL × 100 mL = 100 g. Table 1 indicates that sunscreen B16 is 25% cinoxate by mass, so 0.25 × 100 g = 25 g of cinoxate are present in 100 g of sunscreen. The molecular weight of cinoxate is 0.250 kg/mol, or 250 g/mol, so 25 g of cinoxate is equivalent to 25 g250 g/mol=0.1 mol. An amount of 0.1 mol of cinoxate in 100 mL, or 0.1 L, is a 0.1 mol0.1 L=1.0 M solution.

Second Ionization energy

The second ionization energy is the energy required to remove the second of two electrons from an atom. The second ionization energy tends to increase across a period and to increase up a group; however, ionizations involving core electrons are higher energy than those involving valence electrons. Therefore, group 2 metals will have a lower second ionization energy than group 1.

Bohr model wavelength

The smaller the wavelength, the greater it fell from a higher orbital to a smaller obrtial. Lyman ends at 1 (UV), Balmer 2(Visbile), Paschen 3 (IR)

What is the standard potential E° for the half-reaction below? ClO3−(aq) + 3H+(aq) + 2e− → HClO2(aq) + H2O(l) The slope of a line segment joining two species on a Frost diagram is equal to the standard reduction potential for the couple

This reaction occurs under acidic conditions (ClO3−(aq) is reduced by accepting two electrons under acidic conditions to form HClO2(aq)) Slope = DeltaY/DeltaX HCLO2(Y)-CLO3-(Y)/ HCLO2(X)-CLO3-(X)

What is the mass of water necessary to generate 11.2 L of hydrogen gas if calcium metal reacts with water at standard temperature and pressure (STP)?

Under standard temperature and pressure (STP), which are defined as 0°C (273.15 K) and 1 atm pressure, 1 mole of gas occupies a volume of 22.4 L. 11.2L/22.4 L = .5 moles H2 .5 moles x MM (2 moles water per 1 mole H2) 1mol water x 18.01 g/mol water = 18 g water.

Avogadro's Law

V1/n1=V2/n2 As volume increases, moles increase

A radioactive atom decays by 5 alpha, 3 beta minus, and 2 gamma emissions to yield 211Po. What was the original nucleus?

Well 211Po has 84 protons. 5 alpha emission is +20 amu, +10 protons. Also 3 beta emission is -0 amu, -3 protons. Therefore 211+20 84+10-7 231 91 is Pa

If a channel of a particular cell preferentially transmits smaller ionic species across the membrane, given the following biologically relevant, isoelectronic ions, the channel is LEAST likely to transmit: A.S2− B.Cl− C.K+ D.Ca2+

With charges, they all fall on [Ar]. Anions are larger than cations due to a smaller Zeff. therefore S2- is the largest. A

Compared to the effective nuclear charge of 18O, the effective nuclear charge of 18F is:

Zeff= Z-S where S is the number of core electrons. Zeff,O=ZO−SO=(8−2)=6 Zeff,F=ZF−SF=(9−2)=7 18F Zeff is higher because it has a larger number of protons and same number of core electrons.

Keq=

[products]^coefficients/ [reactants]^coefficients= aA+bB ⇄ cC+dD = [C]^c[D]^d/[A]^a[B]^b However, for a reaction in which one of the reactants is also the solvent (water), the solvent species is omitted from the Keq expression. For example, a 1 M aqueous solution of HC2H3O2 with an equilibrium reaction of HC2H3O2+H2O ⇄ H3O++C2H3O−2 has an associated Keq expression of Keq=[H3O+][C2H3O−2]/[HC2H3O2]

When Gd3+ binds to DOTA, Gd3+ is acting as what kind of acid (arrhenius, bronstedlowry, lewis)

a Lewis acid because it can accept electrons.

Negative delta S

a decrease in entropy aka more ordered.

Combustion reactions

a substance combines with oxygen, releasing a large amount of energy in the form of light and heat. Also water and CO2 are released.

Diamagnetic

all electrons are paired EX: noble gases, alkaline earth metals

electron affinity

amount of energy released when an atom gains an electron (becomes -1 charge)

Positive delta S

an increase in entropy aka disorder, less ordered.

Boyle's law

as pressure increases, volume decreases V1P1=V2P2 Vince Poyle (vince boyle and the poyle's from always sunny).

Diamagnetic

atoms and molecules which have paired electrons that align antiparallel to an applied magnetic field; diamagnetic species are weakly repelled to magnets.

Paramagnetic

atoms and molecules which have unpaired electrons that align parallel to an applied magnetic field; paramagnetic species are weakly attracted to magnets.

Delta H

change in enthalpy

Keq = 1

equilibrium

The amount of product formed in a reaction is dependent on the

equilibrium constant. This constant is not changed by a catalyst, which only changes the rate at which equilibrium is achieved.

-DeltaH

exothermic. Heat is released and temperature rises. More stable. Upward slope on a temperature vs time graph. Product is more stable.

intermolecular forces

forces between molecules. An example is freezing point.

intramolecular forces

forces withan molecules

Why are noble gases the least reactive group on the periodic table?

full valence shell.

Condensation

gas to liquid

Boiling point decreases as

hydrogen bonds decrease

effective nuclear charge trend

increases up and to the right.

An ideal gas

is a hypothetical gas consisting of molecules that have no intermolecular attractions or repulsions, no molecular volume, perfectly elastic collisions, and an average kinetic energy that is directly proportional to the gas temperature.

The Heisenberg uncertainty principle states that

it is impossible to simultaneously know the precise position and velocity of a particle. Electrons in coordination bonds can be described only as probability distributions.

Colligative properties

just the amount matters, not the identity. An example is freezing point. The amount of solute affects freezing point, not the identity of the solute.

Arrhenius equation

k=Ae^(-Ea/RT) 1. The rate constant increases exponentially with increasing temperature. 2. The rate constant increases exponentially with decreasing activation energy. 3. The reaction rate decreases exponentially with increasing activation energy.

Irreversible reactions tend to be under

kinetic control, which favors products whose pathways have the lowest activation energy.

Added solute will

lower its vapor pressure at any given temperature (Raoult's law), causing the briny water to require a higher temperature therefore higher boiling point.

You always forget multiplying by the molar ratio!!!!

molar ratio AHHHHH

Molarity [M]

moles/liters

Alkali and Alkaline earth metals both show an increase in reactivity when

moving down a group.

The difference between the first and second ionization energies for magnesium is approximately 700 kJ/mol. The difference between the second and third ionization energies will likely be:

much higher because the first two electrons removed are valence electrons whereas the next one would be a core electron.

postive delta G

non-spontaneous

0 < Keq < 1

non-spontaneous, Postive Delta G, favors reactant retention ΔG° = −RT ln(Keq)

Shiny nickel metal granules added to orange liquid bromine mixed in alcohol produced a combination reaction yielding a blue-green solution of nickel(II) bromide. In the reaction between Ni and Br2:

oxidation/reduction reaction

Isotopes of the same element exhibit

similar chemical properties but different physical properties (i.e. diff amounts of neutrons).

- delta G

spontaneous

Keq > 1

spontaneous, negative delta G, favors product formation

a catalyst

stabilizes the transition state, and therefore increases the reaction rate without being consumed. A greater catalytic surface area corresponds to a greater reaction rate.

The law of mass action states

that the rate of a reaction is proportional to the molar amount of each reaction component raised to the power of its reaction order. For elementary reactions, the reaction order of each species is equal to its stoichiometric coefficient.

If the energy of the products i more than the energy of the reactants on a graph

the reaction is endergonic (+ΔG) and energy is absorbed. Non-spontaneous

If the energy of the products is less than the energy of the reactants on a graph

the reaction is exergonic (−ΔG) and energy is released. Spontaneous

In a disproportionation reaction,

the same element (at a given oxidation state) undergoes both oxidation and reduction, with some of the atoms being oxidized and other atoms of the same element being reduced. Comparing the oxidation number for each element in the reactants with the oxidation number for the same element in the products enables the identification of a disproportionation.

solvent

the substance in which the solute dissolves

Transition state on a graph

the titty tip.

Rauolt's law

the vapor PRESSURE and freezing point TEMPERATURE are LOWERED as the number of moles of dissolved solute INCREASES

Reversible reactions tend to be under

thermodynamic control, which favors the most stable product.

Intermediate step on a graph

will encompass the largest peak (i.e. the largest energy barrier)