Final Exam
colligative properties
- Boiling point elevation - Vapor pressure lowering - Freezing point depression - Osmotic pressure ALL take into consideration to Van't Hoff factor (i)
three examples of naturally occuring buffers
-blood -sea/ocean -tomato juice
calculate the value of N2 of the reaction below
0.016
Methanol has a normal boiling point of 64.6C and a heat of vaporization. what is the vapor pressure of methanol at 12.0C
0.0993atm
Approximately what temperature does Pb(NO3)2 and KNO3 have the same solubility
0C
What is the hydronium ion concentration of a buffer solution having a pH of 0
1 M
A mixture of 10.0g of Ne and 10.0g Ar have a total pressure of 1.6 atm. what is the partial pressure of Ne
1.1 atm
calculate the concentration of h3o+
1.8x10^-10M, basic
determine the density of CO2 gas at STP
1.96 g/L
The highest pH for an effective buffer occurs when the base is how many times as concentrated as the acid?
10
Dr. Taylor just prepared a mixture of two volatile substances A and B
110 mmHg
If 30.0 L of oxygen at 200C is cooled to 1C at constant pressure, what is the new volume of oxygen
17.4L
The henry's law constant for helium gas in water at 30C is 3.70x10^-4M/atm. when the partial pressure of helium above a sample of water is 0.650 atm, the solubility of helium in the water is
2.41x10^-4
determine the molar solubility for Al(OH)3 in pure water. Ksp for Al(OH)3=1.3x10^-33
2.6x10^-9M
A container of orange juice at 25°C has a hydronium concentration of 1.78 × 10-3M. What is the pH of the juice?
2.75
write a balanced reaction for which of the following rate relationships are true
2N2O->2N2+O2
If the temperature of a gas is tripled and the volume is doubled, the new pressure will be
3-2 the original pressure
The density of a gas was measured at 1.5 atm and 27C and found to be 1.95 g/L. calculate the molar mass of the gas
32g/mol
The pH of a urine was determined to be 7
4
Determine the molar solubility Pb(IO3)2 in pure water. Ksp for Pb(IO3)2 = 2.60x10^-13
4.02x10^-5
Calculate the pH of a buffer that is 0.225M HC2H3O2 and 0.162M KC2H3O2. The Ka for HC2H3O2 is 1.8x10^-5
4.60
A reaction is found to have a rate constant of 3.36x10^4
42.0kJ/mol
The molar solubility og Ba3(PO4)2 is 8.89x10^-9M in pure water. Calculate the Ksp for Ba3(PO4)2
6.00x10^-39
The molar solubility of Ag2S is 1.26x10^-16M in pure water. Calculate the Ksp for Ag2S
8.00x10^-48
Calculate the pH of a solution formed by mixing 250.0 mL of 0.15M NH4+ (acid) with 100.0 mL of 0.20M NH3 (base). The Kb for NH3 is 1.8x10^-5
8.98
What mass of NO2 is contained in a 13.0L tank at 4.58 atm and 385K
86.7g
To what temperature must a baloon, initially at 25C and 2.00L, be heated in order to have a volume of 6.00L
894K
If a chemist wishes to prepare a buffer that will be effective at a pH of 3.00 at 25C, the best choice would be an acid component with a Ka equal to
9.10x10^-4
Vanessa and Melissa decided to prepare a buffer that will be effective at a pH of 3.00 at 25C, the best choice would be an acid component with a Ka eqal to
9.10x10^-4
Calcualte the pH of a solution formed by mixing 250.0 mL of 0.900M NH4Cl with 250.0 mL of 1.60M NH3. The Kb for NH3 is 1.8x10^-5
9.50
From the Ksp values of the ionic salts, which of the following will have the Lowest Solubility in pure water?
Ag2S, Ksp=6.0x10^-51
Define buffer capacity.
Buffer capacity is the amount of acid or base that can be added to a buffer without destroying its effectiveness.
in the following reaction in aqueous solution, the acid reactant is
CH3COOH;CH3COO-
Using the graph below, determine the gas that has the highest density at STP
D
Which of the following solutions would have the highest pH
HCN, 4.9x10^-10
Which of the following acids (listed with Ka values) and their conjugate base would form a buffer with a pH of 2.34
HClO2, Ka = 1.1 × 10-2
Define/explain the solubility product constant (Ksp) of a salt
Ksp is the equilibriuk constant of a salt which determines the extent to which a salt/solid will dissolve in H2O. The higher the Ksp the higher the solubility and vice versa
Place the following substances in order of decreasing boiling point
O2>N2>H2
Give the equation for an unsaturated solution in comparing Q with Ksp
Q<Ksp
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.
When the temperature of NaCl solution is reduced from 100 to 0 which of the following will most likely occur
The NaCl will crystallize out of the solution
Dalton's Law of partial pressures
The total pressure in a vessel is equal to the sum of the partial pressures of the different/individual gases in the vessel/container
LeChatelier's Principle
When a stress is applied to a system at equilibrium, the equilibrium shifts to relieve the stress
Give the expression for the solubility product constant for Cr2(CO3)3
[Cr3+]2[Co3^2-]3
If the pKa of HCHO2 is 3.74 and the pH of an HCHO2/NaCHO2 solution is 3.11, which of the following is TRUE?
[HCHO2]>[NaCHO2]
enzyme
a biological catalyst. a substance that catalyzes biological reactions
Explain how a buffer solution works
a buffer is made from a weak acid and its conjugate base. when an acid is added, the conjugate base neutralizes it and when a base is added the acid part also neutralizes it. this ensures that the buffer maintains a constant pH
Which of the following is true
a buffer is most resistant to pH change when [acid]=[conjugate base]
Ideal solution
a mixture of solutions that have similar intermolecular forces, chemical properties, and therefore mix homogenously
saturated solution
a solution in which the solute dissolved and the solvent absorbed are in dynamic equilibrium
Iso-osmotic solution
a sutiom in which the osmotic pressured are the same. a fluid with an osmotic pressure equal to that of body fluids
acid in vinegar
acetic acid
In terms of solubility concepts, "like dissolves like" means
all of the above (polar solvents are better at dissolving other polar compounds, polar solvent cannot be dissolved in non polar compounds, non polar solvents are better at dissolving other non polar compounds)
Which of the following statements is true?
at very high pressures, a gas will occupy a larger volume than predicted by the ideal gas law
household cleaners like bleach, soap and bathtub cleaners are generally__ in nature
basic
An important buffer in the blood is a mixture of
carbonic acid and bicarbonate ion
Some reactions are more sluggish than others. To speed up these reactions and save energy a(n) ________ is sometimes added.
catalyst
the solubility of most ionic compounds in the graph can be said to be
endothermic
The amount of oxygen dissolved in the waters of the cold arctic ocean is greater, about, equal to or less than the amount of oxygen dissolved in warm tropical waters
greater than
Identify the substance with the highest viscosity
honey
What is the strongest type of intermolecular force present in CH3Ch2CH2NH2
hydrogen bonding
the intermolecular forces that hold the 2 helical strands of the human DNA together is
hydrogen bonding
a fluid with osmotic pressure greater than those of bodily fluids are referred to as
hypersomotic
Which of the following statements is true?
if q>k it means the reverse reaction will proceed to form more reactants
What is the term that refers to liquids that do not dissolve in one another liquid and separate into two layers
immiscible
define/explain a buffer solution
it is a solution that resists changed in pH upon addition of an acid or base. It is usually made from a weak acid & its conjugate base
osmosis
liquid movement from low concentration to high concentration through a semipermeable membrane
Deviations from the ideal gas law are greater at
low temperatures and high pressures
The vapor pressure of a solution is always__that of the pure solvent
lower than
Dr Jessup just purchased a new water bottle for his daughter. The pressure inside the water bottle can accurately be measured by
manometer
What are the units of the rate constant k in the rate law below
mol^-2L^2S^-1
liquids with high surface tension are
more viscous
capilarry action
movement of a liquid up through a thin tube or thin tube-like structure against the force of gravity
A solid can be purified through what technique?
recrystallization
_is applied to roads in winter time so that the ice will melt at a lower temperature
salt
Identify a good buffer.
significant amounts of both a weak acid and its conjugate base
the rate determining step of a reaction
slowest step that determines how fast a mechanism can occur
Acid found in car batteries
sulfuric acid
___ are solutions that are saturated but will not precipitate o crystalize unless disturbed or agitated
super saturated solutions
a_ is used to measure blood pressure of humans
syphgmomanometer
define or explain activation energy of a chemical reaction
the amount of energy required to cause/have a chemical reaction
Which of the above illustrations shows a basic aqueous solution?
the least full oh h3o oh
diffusion of gases is
the movement of gas molecules from a region of high concentration to a region of lower concentration
van't hoff factor
the number of ion/particles that will breakdown when a solute is dissolved
given the following energy profiles, which of the following reactions is endothermic
the one where the reaction starts from the bottom then goes to the top before sloping down to products
