SI: Exam Review 1
1. A 3.75 M HBr solution has a density of 1.27 g/mL. What is the molality of the solution?
2. You have an aqueous solution that is 11.04% by mass NaCl. What is the molality of the NaCl solution?
What is the mole fraction of NaCl?
3. What is the molar mass of a non-dissociating solid if 9.36 g of solid dissolved in 55.0 g of chloroform
solvent to form a solution which has a boiling point of 67.30°C? The boiling point of pure chloroform is
61.70°C and the boiling point constant Kb is 3.63 °C/m.
4. Hydrogen peroxide decays in to water and oxygen in a first-order process. At 20.0 °C, the half-life for
the reaction is 3.92 x 104 seconds. If the initial concentration of hydrogen peroxide is 15 M, what is the
concentration after 7.0 days?
5. The initial rate of the reaction of nitrogen monoxide and oxygen
2 NO (g) + O2 (g) _____> 2 NO2 (g)
was measured at 25 °C for various initial concentrations of NO and O2 shown below.
Experiment
1
2
3
4
5
[NO]
0.020 M
0.020 M
0.020 M
0.040 M
0.010 M
[O2]
0.010 M
0.020 M
0.040 M
0.020 M
0.020 M
Initial Rate (M/s)
0.028
0.057
0.114
0.227
?????
a. Determine the rate equation for the reaction.
b. Predict an observed rate of reaction for Experiment 5.
6. Calculate the heat given off or absorbed when 15.2 g of water is cooled from 105ᵒC to 55ᵒC.
7. The vapor pressure of HCl is 125 torr at 45.6ᵒC and 206.6 torr 58.5ᵒC, what is the heat of vaporization?
8. Draw the plot of first, second and zero order reactions.
9. Draw a reaction energy diagram for a reaction with a forward activation energy of 150 kJ and a
reverse activation energy of 95 kJ. Is the reaction endothermic or exothermic?
10. The aqueous solutions labeled a-f are prepared and the colligative properties for each solution
measured. Answer the following questions using your knowledge of colligative properties.
a. 0.4 m MgBr2
d. 1 m KCl
b. 0.5 m Na2SO4
e. 2 m LiBr
Choose the ONE best answer.
______ The solution with the lowest freezing point.
______ The solution with the lowest boiling point.
______ The solution with the highest boiling point
c. pure water
f. 1 m glucose (C6H12O6)
11. Ideally, colligative properties depend only on
a. The identity of the solute in a solution.
b. The number of solute particles per solvent molecule in a solution.
c. The temperature of a solution.
d. The charge of the ions dissolved in solution.
e. The gas pressure above the surface of a solution.
12. What determines the exponents in a rate law?
1. Experimentation.
2. The coefficients in the balanced equation.
3. The concentrations of the reactants.
a. 1 only
b. 2 only
c. 3 only
d. 1 and 2
e. 2 and 3
13. Ammonia can be formed by reacting nitrogen and hydrogen gases.
N2 (g) + 3 H2 (g) 2 NH3 (g)
If the rate of disappearance of hydrogen is -2.7 x 10-2 M/s, what is the rate of formation of ammonia?
a. 1.8 x 10-2 M/s
b. 2.7 x 10-2 M/s
c. 4.0 x 10-2 M/s
e. 5.4 x 10-2 M/s
e. 8.1 x 10-2 M/s
14. Which intermolecular forces are present in NCl3(s)?
1. London dispersion
2. dipole-dipole
a. 1 and 2
b. 1, 2 and 3
c. 1 only
3. hydrogen bonding
d. 2 only
e. 3 only
15. Which of the following molecular solids will exhibit dipole-dipole intermolecular forces:
NH3, BF3, I2, and H2S?
a. NH3 and H2S
b. NH3, BF3, and H2S
c. I2 only
d. BF3 and I2
e. NH3, BF3, I2, and H2S
16. Which one of the following molecules will have the lowest boiling point?
a. NH3
b. CH4
c. CH3Cl
d. NH2Cl
e. CHCl3
17. What is the half-life of a first order reaction of CO2 if the rate constant is 2.03x10-4s-1?
a. 3.4x104s
b. 1.4x10-3 s
c. 3.4x103 s
d. 1.4x10-4 s
18. According to a typical phase diagram, what state of matter is described as having a high temperature
and low pressure?
a. solid
b. super critical fluid
c. liquid
d. gas
19. Which of the following will have the greatest polarizability?
a. Na
b. Na+
c. Cl
d. Cl20. Viscosity is only affected by temperature?
a. true
b. false
21. Which of the following will have the highest surface tension?
a. NH3
b. CCl4
c. CO2
d. H2S
22. Solids have the lowest entropy?
a. true
b. false
23.Water has hydrogen bonding, therefore water has a low boiling point?
a. true
b. false
24. What type of intermolecular forces are found in SO2?
1. London dispersion
2. dipole-dipole
a. 1 and 2
b. 1, 2, and 3 c. 1 only
d. 2 only
3. hydrogen bonding
e. 3 only
25. Adding a solute to a solvent will increase the vapor pressure?
a. true
b. false