CHE 134 smr ‘11Exam 1 REVIEW Sheet

1. Helium atoms do not combine to form He2 molecules, yet He atoms do attract one another weakly through…

2. Which one of the following substances will have both dispersion forces and dipole-dipole forces? HCl Br2 H2 CO2 BCl3

3. Name characteristics that indicate the presence of weak intermolecular forces in a liquid?

4. Each of the following substances is a liquid at –50°C. Place these liquids in order of increasing vapor pressure: dimethyl ether (CH3OCH3), propane (C3H8), and ethanol (CH3CH2OH).

5. Is this statement true? The freezing point of a liquid does not change as the atmospheric pressure changes. Explain.

6. Which one of the following substances should exhibit hydrogen bonding in the liquid state? He PH3 H2S CH4 CH3OH

7. Which of the responses includes all of the following that can form hydrogen bonds with water molecules?

(1) Na+ (2) CH3COOH (3) C2H6 (4) CH3NH2

8. Butter melts over a range of temperature, rather than with a sharp melting point. Butter is classified as a/an (metallic crystal, covalent solid, molecular crystal, amorphous solid, ionic crystal)

9. Which of the following compounds should be soluble in CCl4? NaCl, H2O, NaOH, C2H18, or None of these

10. What is the molality of a solution that is 3.68 % by mass calcium chloride.

11. Calculate the percent by mass of potassium nitrate in a solution made from 45.0 g KNO3 and 295 mL of water. The density of water is 0.997 g/mL.

12. Which of the following has the greater molal concentration (molality)?1.0 m KNO3 , 1.0 M KNO3 , or both have the same molality?

13. The solubility of nitrogen gas at 25°C and a nitrogen pressure of 522 mmHg is 4.7 10–4 mol/L. What is the value of the Henry's Law constant in mol/L·atm?

14. What is the freezing point of an aqueous solution of a nonvolatile solute that has a boiling point of 102.5°C? For water Kf = 1.86°C/m and Kb = 0.52°C/m.

15. The reaction A + 2B products has the rate law, rate = k[A][B]3. If the concentration of B is doubled while that of A is unchanged, by what factor will the rate of reaction increase?

16. What are the appropriate units for a second-order rate constant?Prof Petro

CHE 134 smr ‘11Exam 1 REVIEW Sheet

17. For the overall chemical reaction shown below, which one of the following statements can be rightly assumed? 2H2S(g) + O2(g) 2S(s) + 2H2O(l)

a) The reaction is third-order overall.b) The reaction is second-order overall.c) The rate law is, rate = k[H2S]2 [O2].d) The rate law is, rate = k[H2S] [O2].e) The rate law cannot be determined from the information given

18. At 700 K, the rate constant for the following reaction is 6.2 10–4 min–1.

How many minutes are required for 20% of a sample of cyclopropane to isomerize to propene?

19. A certain first-order reaction A B is 25% complete in 42 min at 25°C. What is its rate constant?

20. Which one of the following changes would alter the rate constant (k) for the reaction 2A + B products?

21. For the chemical reaction A B + C, a plot of [A]t versus time is found to give a straight line with a negative slope. What is the order of reaction with respect to A?

22. Aspirin, C9H8O4, slowly decomposes at room temperature by reacting with water in the atmosphere to produce acetic acid, HC2H3O2, and 2-hydroxybenzoic acid, C7H6O3 (this is why old bottles of aspirin often smell like vinegar):

C9H8O4 + H2O HC2H3O2 + C7H6O3

Concentration and rate data for this reaction are given below.

[C9H8O4] (M) [H2O] (M) Rate (M/s) 0.0100 0.0200 2.4 10–13

0.0100 0.0800 9.6 10–13

0.0200 0.0200 4.8 10–13

Write the rate law for this reaction and calculate k (be sure to include the correct units).

ANSWER KEY: Answers only. The work can be seen through examples, power points and notes.1. dispersion forces

Prof Petro

CHE 134 smr ‘11Exam 1 REVIEW Sheet

2. HCl3. low heat of vaporization4. ethanol < dimethyl ether < propane5. false6. CH3OH7. CH3COOH and CH3NH2

8. amorphous solid9. C8H18

10. 0.344 m11. 13.3 %12. 1.0 M KNO3

13. 6.8 10–4 mol/L·atm14. –8.94°C15. 816. 1/M·s17. The rate law cannot be determined from the information given18. 360 min19. 6.8 10–3 min–1

20. increasing the temperature21. zeroth22. The rate law is rate = k[C9H8O4][H2O], and the rate constant is 1.2 10–9

Prof Petro