Chemistry - A Molecular Science

Chapter 7 States of Matter and Changes in State

therefore, a function of pressure. Typically, when

the boiling point of a substance is given,

it is the normal boiling point (that is, the temperature at which the vapor pressure is 1 atm). The critical temperature is the maximum temperature at which the liquid can exist, and the pressure required to liquefy a gas at the critical temperature is called the critical pressure. Finally, the solid

U

vapor equilibrium is reached when the rate of sublimation (solid

→

vapor) equals the rate of deposition (solid

←

vapor). A graph that shows the phase of a

substance as a function of its temperature and pressure is called a phase diagram.

After studying the material presented in this chapter, you should be able to: 1. determine the pressure of a gas given the relative heights of the mercury columns in a

manometer and the barometric pressure (Section 7. 1);

2. convert from degrees Celsius to kelvins (Section 7.1); 3. use the ideal gas law, PV = nRT, to determine one unknown given the other variables

(Section 7.1);

4. determine the partial pressures of each of t

he gases in a mixture of gases (Section 7.1);

5. define “molar concentration” and determine

the molarity of a gas (Section 7.1);

6. explain the postulates of kinetic-molecular theory (Section 7.2); 7. estimate the thermal energy of a syst

em from its temperature (Section 7.2);

8. distinguish between intermolecular and intramolecular forces (Section 7.3); 9. describe a temporary dipole and how it

leads to dispersion forces (Section 7.3);

10.

use Lewis structures to predict if a molecu

le contains a permanent dipole (Section 7.3);

11.

explain the effects that hydrogen bonding has on water (Section 7.3);

12.

describe the general features

of a solid (Section 7.4);

13.

define viscosity and surface tension and expl

ain how they vary with the strength of the

intermolecular interact

ions (Section 7.5);

14.

define meniscus and explain why it can be

either convex or concave (Section 7.5);

15.

define the heats of fusion, vaporization, and sublimation (Section 7.6);

16.

define melting point, vapor pressure, boiling point, critical point and explain how they vary with intermolecular forces (Section 7.6);

17.

describe changes in state at a molecular level (Section 7.6); and

18.

interpret a phase diagram (Section 7.6).

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