SI: Week 5 Session 2 2/10/16
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. Pure iodine (104.0 g) is dissolved in 315. g of CCl4 at 65.0°C. Given the vapor pressure of CCl4 at this temperature is 529 mm Hg, what is the vapor pressure of the CCl4-I2 solution at 65.0 °C? Assume that I2 does not contribute to the vapor pressure.
5. 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?
6. The density of an unknown metal is 12.3 m/cm3 and its atomic radius is 0.134 nm. It is face centered cubic. What is the metal?
7. 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 / [NO] / [O2] / Initial Rate (M/s)1 / 0.020 M / 0.010 M / 0.028
2 / 0.020 M / 0.020 M / 0.057
3 / 0.020 M / 0.040 M / 0.114
4 / 0.040 M / 0.020 M / 0.227
5 / 0.010 M / 0.020 M / ?????
- Determine the rate equation for the reaction.
b. Predict an observed rate of reaction for Experiment 5.
8. 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. 0.4m MgBr2b. 0.5 m Na2SO4c. pure water
d. 1mKCle. 2 mLiBrf. 1 mglucose (C6H12O6)
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
9. 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.
10. 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 onlyb. 2 onlyc. 3 onlyd. 1 and 2e. 2 and 3
11.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/sb. 2.7 x 10-2 M/sc. 4.0 x 10-2 M/s
e. 5.4 x 10-2 M/se. 8.1 x 10-2 M/s
12. Which intermolecular forces are present in NCl3(s)?
1. London dispersion2. dipole-dipole3. hydrogen bonding
a. 1 and 2b. 1, 2 and 3 c. 1 onlyd. 2 only e. 3 only
13. Which of the following molecular solids will exhibit dipole-dipole intermolecular forces:
NH3, BF3, I2, and H2S?
a. NH3 and H2Sb. NH3, BF3, and H2Sc. I2 only
d. BF3 and I2e. NH3, BF3, I2, and H2S
14. Which one of the following molecules will have the lowest boiling point?
a. NH3b. CH4c. CH3Cld. NH2Cle. CHCl3
15. Predict the normal boiling point (1 atm pressure) for H2Se based on observations that H2O boils at 100ᵒC and H2S boils at –61ᵒC and H2Te boils at ~ 0ᵒC .
a. – 82 °Cb. – 63 °Cc. – 42 °Cd. 120 °C
16. Which of the following has the highest boiling point?
a. 1 M NaClb. 2 M AgCl c. 0.5 M MgCl2d. 1 M glucose
17. What is the half-life of a first order reaction of CO2 if the rate constant is 2.03x10-4s-1?
a. 3.4x104sb. 1.4x10-3 sc. 3.4x103 sd. 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. solidb. super critical fluidc. liquidd. gas
19. Which of the following will have the greatest polarizability?
a. Nab. Na+c. Cld. Cl-
20. What type of intermolecular forces are found in SO2?
1. London dispersion2. dipole-dipole3. hydrogen bonding
a. 1 and 2b. 1, 2, and 3 c. 1 onlyd. 2 onlye. 3 only
21. Adding a solute to a solvent will increase the vapor pressure?
a. trueb. false