WorksheetsGeneral Chem-Exam 2
Total questions: 31
Worksheet time: 1hrs 23mins
Calculate the mole fraction of ethyl alcohol, C2H5OH, in a solution that contains 230. grams of C2H5OH and 312 grams of benzene, C6H6.
0.56
0.12
1.8
2.3
What is the molality of an aqueous solution that is 10.0% ethanol, C2H5OH, by mass?
1.38 m
7.22 m
2.42 m
2.01 m
An aqueous solution contains 64.0 g of ethanol (C2H5OH) in 122.0 g of total solution. The mole fraction of ethanol is:
0.301
0.205
0.387
None of the above
Identify the CORRECT statement concerning the solubility of various solutes:
NaCl would be soluble in the hydrocarbon solvent hexane.
KCl would be soluble in the hydrocarbon solvent benzene.
CaCl2 would be soluble in water.
Alcohols and water are generally immiscible.
What is the molarity of a solution in which 50.0 mL of chloroform, CHCl3, are placed in a 100.0 mL volumetric flask and the flask is filled to the mark with acetone? The density of pure CHCl3 is 1.483 g/mL.
5.22 M
6.21 M
0.500 M
0.423 M
Which substance would have the highest solubility in hexane, C6H14?
NaCl
H2O
S8
NH3
Solubility of gases in liquids usually decreases with increasing temperature.
True
False
What is the vapor pressure of a aqueous solution containing 10 % (by weight) ethylene glycol (62 g/mol) at 25 °C. PH2O = 24.3 torr at 25°C?
25.1 torr
23.5 torr
0.761 torr
18.9 torr
"The amount of a gas dissolved in a solution is directly proportional to the pressure of the gas above the solution" is:
Raoult's law
Henry's law
an example of osmotic pressure
van't Hoff's method
Calculate the freezing point of a solution that contains 8.0 g of sucrose (C12H22O11) in 100. g of H2O. Kf for H2O = 1.86°C/m.
- 0.044°C
- 0.22°C
- 0.39°C
- 0.44°C
If 4.27 grams of sucrose, C12H22O11, are dissolved in 15.2 grams of water, what will be the boiling point of the resulting solution? Kb for water = 0.512 °C/m.
99.626 °C
100.42 °C
101.42 °C
101.64 °C
What are the ideal van't Hoff factors for the following compounds:
Ba(OH)2, C6H12O6, K3PO4, HNO3 ?
2, 1, 2, 2
6, 3, 5, 5
3, 1, 4, 2
none of the above
The solubility of CO2 gas in water _____ with increasing pressure (of CO2) and _____ with increasing temperature.
increases, increases
decreases, decreases
increases, decreases
remains constant, decreases
Identify the INCORRECT statement below concerning chemical kinetics:
The rate of a chemical reaction is affected by the temperature of the reaction.
The rate law of a chemical reaction bears no relationship with the balancing coefficients of the overall reaction.
The rate constant of a reaction generally depends on the concentrations of species.
The rate of a chemical reaction changes with time.
The rate law for the iodine clock reaction is given by: Rate = k[IO3- ][I- ]2[H+]2
This reaction is first order with respect to IO3- and third order overall.
This reaction is second order with respect to I- and 3rd order overall.
This reaction is first order with respect to IO3- and fifth order overall.
This reaction is third order with respect to H+.
Consider the following kinetic data collected at the very beginning of a reaction:
Run # Initial [A] Initial [B] Initial Rate of Reaction
(mol/L) (mol/L) (mol/L-s)
----------------------------------------------------------------
1 0.10 0.10 0.0090
2 0.20 0.10 0.036
3 0.10 0.20 0.018
Which of the following is an appropriate expression for the rate law and rate constant?
Rate = k[A]2[B]; k = 9.0 L2/mol2-s
Rate = k[A]2[B]; k = 0.9 L2/mol2-s
Rate = k[A][B]; k = 0.9 L / mol-s
Rate = k[A]4[B]2; k = 9.0 x 103 L / mol-s
In the overall reaction given by:
H2(g) + 2 ICl(g) --> I2(g) + 2 HCl(g)
the concentration of all species are changing by the same amount at all times.
the concentration of H2 decreases at the same rate as ICl.
the concentration of HCl increases twice as fast as I2.
Consider the following rate law expression: Rate = k[A]2[B]. Which of the following is NOT TRUE about the reaction having this expression?
The reaction is overall third order.
The reaction is first order in B.
Doubling the concentration of A doubles the rate.
The reaction is second order in A.
The gas phase reaction A + B ---> C has a reaction rate which is experimentally observed to follow the relationship Rate = k[A]2[B]. If the concentration of A is tripled and the concentration of B is doubled, the reaction rate would be increased by a factor of _____.
9
6
18
12
A reaction has the following stoichiometry:
H2 + 2 ICl ---> I2 + 2 HCl
Which of the following would be a correct definition of the rate?
Rate = +(1/2)Δ[HCl]/Δt
Rate = +Δ[HCl]/Δt
Rate = +Δ[H2]/Δt
all are correct
Given the following data for the NH4+ + NO2- ---> N2 + 2H2O reaction:
Trial [NH4+] [NO2-] Rate
----------------------------------------------------------------------------------------------------------------------------------
1 0.010 M 0.020 M 0.020 M/s
2 0.015 0.020 0.030
3 0.010 0.010 0.005
The rate law for the reaction is:
rate = k[NH4+][NO2-]
rate = k[NH4+][NO2-]2
rate = k[NH4+]2[NO2-]
rate = k[NH4+]2 [NO2-]2
In a given 1st order reaction A ---> products, the initial concentration of A is 0.40 M. What will be the concentration of A after 15 seconds if the half-life of the reaction is 3 seconds?
8.0 x 10-2 M
2.66 x 10-2 M
2.5 x 10-2 M
1.25 x 10-2 M
The catalytic converter in an automobile uses NiO and Pt metal to speed the combustion of CO to CO2. This is an example of:
homogeneous catalysis
heterogeneous catalysis
acid hydrolysis
enzyme catalysis
The relationship between the rate constant and temperature is expressed by the:
Arrhenius equation
integrated rate equation
reaction mechanism
rate law
Cyclopropane rearranges to form propene:
CH2CH2CH2 --> CH2=CHCH3
by first-order kinetics. The rate constant is
k = 2.74 x 10-3 s-1. The initial concentration of cyclopropane is 0.290 M. What will be the concentration of cyclopropane after 100 seconds?
0.220 M
2.74 x 10-1 M
0.760 M
None of the above
The rate constant for the first order reaction A ---> B + C is
k = 3.3 x 10-2 min-1 at 57 K. What is the half-life for this reaction at 57 K?
61 min
1200 min
21 min
30 min
For the gas phase decomposition of dinitrogen pentoxide at 335 K the average rate of disappearance of N2O5 over the time period from t = 0 s to t = 154 s is found to be 6.0 x 10-4 M s-1.
2 N2O5 ---> 4 NO2 + O2
The average rate of formation of NO2 over the same time period is how many moles per liter per second?
6.0 x 10-4 M s-1
1.2 x 10-3 M s-1
3.0 x 10-4 M s-1
2.4 x 10-3 M s-1
In a study of the gas phase decomposition of sulfuryl chloride SO2Cl2 ---> SO2 + Cl2 at 600 K the concentration of SO2Cl2 was followed as a function of time. It was found that a graph of ln[SO2Cl2] versus time in minutes gave a straight line with a slope of -3.9 x 10-3 min-1 and a y-intercept of -5.9. Based on this plot, the reaction is what order in SO2Cl2 and the rate constant for the reaction is what value?
1st order, k = 5.9 min-1
2nd order, k = 5.9 min-1
1st order, k = 3.9 x 10-3 min-1
2nd order, k = 3.9 x 10-3 min-1
The gas phase decomposition of nitrosyl chloride 2 NOCl ---> 2 NO + Cl2 at 400 K is second order in NOCl. In one experiment, when the initial concentration of NOCl was 3.78 x 10-2 M, the concentration of NOCl dropped to 3.82 x 10-3 M after 3.07 x 105 seconds had passed. Based on these data, the rate constant for the reaction is what value ?
4.97 x 10-3 M-1s-1
4.97 x 10-3 M-1s-1
7.67 x 10-4 M-1s-1
3.25 x 10-6 M-1s-1
Consider the mechanism:
O3(g) <---> O2(g) + O(g); fast
O(g) + O3(g) ---> 2 O2(g); slow
An intermediate in this reaction is:
O3(g)
O2(g) and O(g)
There is no intermediate in this reaction
O(g)
When a catalyst is used in a reaction,
the forward reaction is increased while the reverse reaction is retarded.
it does not affect the final amounts of reactants and products.
the activation energy of the reverse reaction is increased.
