Chem 162 Final Exam UPDATED ACTUAL QUESTIONS
AND CORRECT Answers
If 0.100 mol of solute is added to 0.500 L of solvent with b.
a density of 0.790 g/mL, the molality of the solution is
a. 0.166 m
b. 0.253 m
c. 1.27x10^-4 m
d. none
e. 0.200 m
This question counts the weight of two questions. The k=0.01136 1/hr
half-life of a reactant in a first-order reaction was 0.430 M
measured to be 6.10 hours. If the starting concentration
is 1.00 M, what is the remaining concentration after 7.43
hours?
The first-order rate equations are
ln [A]t = -kt + ln [A]0 and t1/2=0.693/k
Calculate k, the rate constant and select the correct
units for k (leave one extra significant figure to prevent
rounding error).
Calculate the remaining concentration after 7.43 hours.
Adding 17.5 g of an unknown compound to 100.0 g of 0.9677m
water results in a freezing point lowering of -1.80 °C. 1.81 g/mol
Calculate the molality and molar mass of the unknown
compound. You may assume that the density of water is
1.00 g/mL, and Kf for water is 1.86 °C/m.
Equation: ΔTf = Kf m
,Select the correct expression for the rate of the rate= -1/2[H2O2]/d. t
following reaction, in terms of the concentrations of =1/2[h2o]/d.t
reactants and products. =1/1[o2]/d. t
2 H2O2 → 2 H2O + O2
the definition of molality (m) is e.
a. mol solute per liter of solution
b. none
c. mol solute per liter of solvent
d. mol solute per kilogram of solution
e. mol solute per kilogram of solvent
the rate law for a second-order reaction is written rate=k[A]^2
You would expect a molecule of the formula C8H18 to a.
be most soluble in
a. C6H6
b. none
c. H2O
d. CH3OH
e. NH3
gases are most soluble in water at d.
a. high temps and low pressures
b. high temps and high pressures
c. low temps and low pressures
d. low temps and high pressures
If a nonvolatile solute is added to a solvent, you would a.
expect the mixture to show
a. Freezing point depression and boiling point elevation
b. Freezing point elevation and boiling point
depression
c. None of these
If you are given the rate constant of a reaction at four x: 1/T
different temperatures, how would you calculate the y: ln k
activation energy from the equation Ea: slope=-Ea/R
ln k= -Ea/RT+ln A
plot what as x?
plot what as why?
activation energy calculated from?
In the energy diagram below, the activation energy of bottom of curve to top of curve
the forward reaction is shown by which arrow?
If a solution contains 30. ppm (parts per million) of a e.
pollutant, what percentage is this?
a. 3.0 x 10-4 percent
b. 0.30 percent
c. None of these
d. 3.0 x 10-5 percent
e. 0.0030 percent
, The effect of a catalyst on the activation energy of a a.
reaction is to
a. Lower the activation energy
b. Raise the activation energy
c. None of these
An elementary reaction is a reaction that occurs in a T
single step.
The step that determines the rate of an overall reaction F
is the fast step.
According to the Arrhenius equation, the rate constant T
k depends on temperature.
For any reaction, the order of the reaction is given by F
the balancing coefficients.
A catalyst is used up in a chemical reaction. F
If the following reaction is at equilibrium, what happens c.
if we add more CoO(s) to the following reaction:
CoO(s) + H2(g) ⇄ Co(s) + H2O(g)
Select one:
a. The reaction shifts backward
b. The reaction shifts forward
c. No shift
For the reaction 5A + B → 3C which fraction is equal to -1/5(delta[A]/delta t)
the rate?
The equilibrium constant at a given temperature for the d.
reaction
H2(g) + Br2(g) ⇆ 2HBr(g)
is 1.6 × 105. The value of K for the reverse reaction is
Select one:
a. 6.3 × 10-5
b. -1.6 × 105
c. 1.6 × 10-5
d. 6.3 × 10-6
e. 1.6 × 105
What is the equilibrium constant expression for the [H2O]/[H2]
following reaction:
CoO(s) + H2(g) ⇆ Co(s) + H2O(g)
Which substance would be the most soluble in a a.
nonpolar solvent?
Select one:
a. N2
b. H2O
c. NO
AND CORRECT Answers
If 0.100 mol of solute is added to 0.500 L of solvent with b.
a density of 0.790 g/mL, the molality of the solution is
a. 0.166 m
b. 0.253 m
c. 1.27x10^-4 m
d. none
e. 0.200 m
This question counts the weight of two questions. The k=0.01136 1/hr
half-life of a reactant in a first-order reaction was 0.430 M
measured to be 6.10 hours. If the starting concentration
is 1.00 M, what is the remaining concentration after 7.43
hours?
The first-order rate equations are
ln [A]t = -kt + ln [A]0 and t1/2=0.693/k
Calculate k, the rate constant and select the correct
units for k (leave one extra significant figure to prevent
rounding error).
Calculate the remaining concentration after 7.43 hours.
Adding 17.5 g of an unknown compound to 100.0 g of 0.9677m
water results in a freezing point lowering of -1.80 °C. 1.81 g/mol
Calculate the molality and molar mass of the unknown
compound. You may assume that the density of water is
1.00 g/mL, and Kf for water is 1.86 °C/m.
Equation: ΔTf = Kf m
,Select the correct expression for the rate of the rate= -1/2[H2O2]/d. t
following reaction, in terms of the concentrations of =1/2[h2o]/d.t
reactants and products. =1/1[o2]/d. t
2 H2O2 → 2 H2O + O2
the definition of molality (m) is e.
a. mol solute per liter of solution
b. none
c. mol solute per liter of solvent
d. mol solute per kilogram of solution
e. mol solute per kilogram of solvent
the rate law for a second-order reaction is written rate=k[A]^2
You would expect a molecule of the formula C8H18 to a.
be most soluble in
a. C6H6
b. none
c. H2O
d. CH3OH
e. NH3
gases are most soluble in water at d.
a. high temps and low pressures
b. high temps and high pressures
c. low temps and low pressures
d. low temps and high pressures
If a nonvolatile solute is added to a solvent, you would a.
expect the mixture to show
a. Freezing point depression and boiling point elevation
b. Freezing point elevation and boiling point
depression
c. None of these
If you are given the rate constant of a reaction at four x: 1/T
different temperatures, how would you calculate the y: ln k
activation energy from the equation Ea: slope=-Ea/R
ln k= -Ea/RT+ln A
plot what as x?
plot what as why?
activation energy calculated from?
In the energy diagram below, the activation energy of bottom of curve to top of curve
the forward reaction is shown by which arrow?
If a solution contains 30. ppm (parts per million) of a e.
pollutant, what percentage is this?
a. 3.0 x 10-4 percent
b. 0.30 percent
c. None of these
d. 3.0 x 10-5 percent
e. 0.0030 percent
, The effect of a catalyst on the activation energy of a a.
reaction is to
a. Lower the activation energy
b. Raise the activation energy
c. None of these
An elementary reaction is a reaction that occurs in a T
single step.
The step that determines the rate of an overall reaction F
is the fast step.
According to the Arrhenius equation, the rate constant T
k depends on temperature.
For any reaction, the order of the reaction is given by F
the balancing coefficients.
A catalyst is used up in a chemical reaction. F
If the following reaction is at equilibrium, what happens c.
if we add more CoO(s) to the following reaction:
CoO(s) + H2(g) ⇄ Co(s) + H2O(g)
Select one:
a. The reaction shifts backward
b. The reaction shifts forward
c. No shift
For the reaction 5A + B → 3C which fraction is equal to -1/5(delta[A]/delta t)
the rate?
The equilibrium constant at a given temperature for the d.
reaction
H2(g) + Br2(g) ⇆ 2HBr(g)
is 1.6 × 105. The value of K for the reverse reaction is
Select one:
a. 6.3 × 10-5
b. -1.6 × 105
c. 1.6 × 10-5
d. 6.3 × 10-6
e. 1.6 × 105
What is the equilibrium constant expression for the [H2O]/[H2]
following reaction:
CoO(s) + H2(g) ⇆ Co(s) + H2O(g)
Which substance would be the most soluble in a a.
nonpolar solvent?
Select one:
a. N2
b. H2O
c. NO
