Unit 4 Quest Review Name # Phases of Matter Block AP Chemistry

Section I. Multiple Choice 1. In which of the following liquids do the

intermolecular forces include dipole-dipole forces?(A) F2

(B) CH4

(C) CF4

(D)CH2F2

(E) None of these

2. A sample of a hard, solid binary compound at room temperature did not conduct electricity as a pure solid but became highly conductive when dissolved in water. Which of the following types of interactions is most likely found between the particles in the substance?(A) Ionic bonds(B) Metallic bonds(C) Nonpolar covalent bonds(D) Hydrogen bonds(E) Polar covalent bonds

3. Which of the following molecules is least soluble in water?

4. Under which of the following conditions of temperature and pressure will N2 gas be expected to behave most like an ideal gas?(A) 50 K and 0.10 atm(B) 50 K and 5.0 atm(C) 500 K and 0.10 atm(D) 500 K and 50 atm(E) 100 K and 5.0 atm

5. At room temperature I2(s) is a molecular solid. Which of the following provides a characteristic of I2(s) with a correct explanation?

(A) It has a high melting point because it has weak intermolecular forces

(B) It is hard because it forms a three-dimensional covalent network

(C) It is not a good conductor of electricity because its valence electrons are localized in bonding and nonbonding pairs

(D) It is very soluble in water because its molecules are polar

(E) None of these

6. Based on the information in the table below, which liquid, CS2(l) or CCl4(l), has the higher equilibrium vapor pressure at 25oC, and why?

(A)CS2 because it has stronger London dispersion forces

(B) CS2 because it has weaker London dispersion forces

(C) CCl4 because it has stronger London dispersion forces

(D)CCl4 because it has weaker London dispersion forces

(E) CS2 and CCl4 will have equal vapor pressures

7. A 4 L sample of N2(g) and a 2 L sample of Ar(g), each originally at 1 atm and 0°C, are combined in a 2 L tank. If the temperature is held constant, what is the total pressure of the gases in the tank?(A) 1 atm(B) 2 atm(C) 3 atm(D) 4 atm(E) 5 atm

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8. A vessel contains Xe(g) at a high pressure. Which of the following statements best helps to explain why the measured pressure is significantly greater than the pressure calculated using the ideal gas law?(A)The molar mass of Xe is relatively large (B) A significant number of Xe2 molecules form(C) The attractive forces among Xe atoms cause

them to collide with the walls of the container with less force

(D)The combined volume of the Xe atoms is too large to be negligible compared with the total volume of the container

(E) None of these

9. Which of the following diagrams best depicts an alloy of Zn and Cu?

10.

At constant temperature, the behavior of a sample of a real gas more closely approximates that of an ideal gas as its volume is increased because the –(A)Collisions with the walls of the container

become less frequent(B) Average molecular speed decreases(C) Molecules have expanded(D)Average distance between molecules

becomes greater(E) Average molecular kinetic energy decreases

11. Three rigid containers at 273 K contain He(g), Ne(g), and SO2(g) respectively. The average speed of the gas particles is –

(A) Greatest for He(g)(B) Greatest for Ne(g)(C) Greatest for SO2(g)(D) The same for all three gases

12. If the pressure on a gas doubles, the kinetic energy –(A) Doubles(B) Triples(C) Halves(D) Quarters(E) Remains the same

13. How much energy is required to boil 36 g of water at 100oC? (The molar mass of water is 18 g/mol and the heat of vaporization is 40.7 kJ/mol.)(A) 40.7 kJ (C) 10.4 kJ(B) 81.4 kJ (D) 5.2 kJ

Questions 14-15 refer to the following heating curve for methane, CH4.

14. What is the melting point for methane?(A) 60 K(B) 90 K(C) 110 K(D) 140 K

15. The enthalpy of vaporization of water is 40.7 kJ/mol. Which of the following best explains why the enthalpy of vaporization of methane is less than that of water?(A)Methane does not exhibit hydrogen bonding,

but water does(B) Methane has weaker dispersion forces(C) Methane has a smaller molar mass(D)Methane has a much lower density

Section II. Free-Response

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1. 6.25 x 10-2 moles of F2(g) are stored in a sealed container. At 25oC, the pressure of the F2(g) in the container is 1.3 atm. Calculate the volume, in L, of the sealed container.

2. The normal boiling point of Cl2(l) (238 K) is higher than the normal boiling point of HCl(l) (188 K). Account for the difference in normal boiling points based on the types of intermolecular forces in the substances. You must discuss both of the substances in your answer.

3. Structures of the pyridine molecule and benzene molecular are shown to the right. Pyridine is soluble in water, whereas benzene is not soluble in water. Account for the difference in solubility. You must discuss both of the substances in your answer.

4. The structures for glycerol and trichloropropane are given below.

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a. For each compound, identify all types of intermolecular forces present.

b. Which compound would be expected to have the higher boiling point?

5. The table below shows some data for the compounds CH3Cl and CH3Br.

a. Identify all the types of intermolecular forces that exist among molecules of CH3Cl(l).

b. Calculate the pressure in a 2.00 mL vial containing a 1.00 g sample of CH3Cl(l) at 298 K assuming that all the liquid vaporized.

c. Explain why it would be unsafe to leave the vial from part b on the lab bench at 298 K.

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