Chemistry for Changing Times 12 th Edition Hill and Kolb Chapter 6 Gases, Liquids, Solids, and Intermolecular Forces John Singer Jackson Community College, Jackson, MI © 2010 Pearson Prentice Hall, Inc.

6/2 Intermolecular Forces and the States of Matter Solids: The particles of a solid have fixed positions and exhibit motions of vibration. Liquids: The particles of a liquid are free to move within the confines of the liquid. Gas: The particles of a gas are far apart and move randomly and rapidly.

© 2010 Pearson Prentice Hall, Inc. 6/3 Intermolecular Forces and the States of Matter Melting point: The temperature at which a solid becomes a liquid. Vaporization: The process of a liquid becoming a gas. Boiling point: The temperature at which the particles of a liquid escape and become a gas.

© 2010 Pearson Prentice Hall, Inc. 6/4 Intermolecular Forces and the States of Matter Condensation: The process by which a gas becomes a liquid. Freezing: The process by which a liquid becomes a solid. This occurs at the freezing point, which is the same as the melting point. Sublimation: When a solid changes directly from the solid to the gaseous state.

© 2010 Pearson Prentice Hall, Inc. 6/5 Intermolecular Forces and the States of Matter

© 2010 Pearson Prentice Hall, Inc. 6/6 Intermolecular Forces and the States of Matter Ionic bonds: Ionic bonds are the strongest of forces that hold matter in the condensed states.

© 2010 Pearson Prentice Hall, Inc. 6/7 Intermolecular Forces and the States of Matter Dipole forces: Polar molecules exist as dipoles. These oppositely charged ends will attract each other.

© 2010 Pearson Prentice Hall, Inc. 6/8 Intermolecular Forces and the States of Matter Hydrogen bonds: When a hydrogen atom is covalently bonded to a highly electronegative atom like nitrogen, oxygen, or fluorine (N,O,F), it can exhibit an additional polar attraction. This attraction is called a hydrogen bond.

© 2010 Pearson Prentice Hall, Inc. 6/9 Intermolecular Forces and the States of Matter Dispersion forces: Nonpolar molecules exhibit a dynamic induced dipole. The strength of this force increases with molecular weight and is known as dispersion forces or London dispersion forces.

© 2010 Pearson Prentice Hall, Inc. 6/10 Intermolecular Forces and the States of Matter Solution: An intimate, homogeneous mixture of two or more substances. Solute: A substance that is dispersed in a solution. Solvent: A substance doing the dissolving, usually present in greatest quantity.

© 2010 Pearson Prentice Hall, Inc. 6/11 Intermolecular Forces and the States of Matter

© 2010 Pearson Prentice Hall, Inc. 6/12 Intermolecular Forces and the States of Matter “Like dissolves like”: Solutions form most readily when both the solute and solvent have similar intermolecular forces.

© 2010 Pearson Prentice Hall, Inc. 6/13 Intermolecular Forces and the States of Matter Ionic substances dissolve in water through ion- dipole interactions.

© 2010 Pearson Prentice Hall, Inc. 6/14 The Gas Laws Kinetic Molecular Theory of a Gas Postulates: 1.The particles of a gas are in rapid constant motion. 2.The particles of a gas are tiny compared to the distance between them. 3.There is little attraction between the particles of a gas. 4.Collisions between gas molecules are perfectly elastic. 5.Temperature is a measure of the average kinetic energy of gas molecules.

© 2010 Pearson Prentice Hall, Inc. 6/15 The Gas Laws

© 2010 Pearson Prentice Hall, Inc. 6/16 The Gas Laws Boyle’s law: At constant temperature, the volume of a gas is inversely proportional to its pressure. V α 1/P V = a/P PV = a V 1 P 1 = V 2 P 2

© 2010 Pearson Prentice Hall, Inc. 6/17 The Gas Laws Boyle’s law: At constant temperature, the volume of a gas is inversely proportional to its pressure.

© 2010 Pearson Prentice Hall, Inc. 6/18 The Gas Laws Charles’s law: At constant pressure, the volume of a gas is directly proportional to its absolute temperature. V α T V = bT V/T = b V 1 /T 1 = V 2 /T 2

© 2010 Pearson Prentice Hall, Inc. 6/19 The Gas Laws Charles’s law: At constant pressure, the volume of a gas is directly proportional to its absolute temperature.

© 2010 Pearson Prentice Hall, Inc. 6/20 The Gas Laws Charles’s Law

© 2010 Pearson Prentice Hall, Inc. 6/21 The Gas Laws Avogadro’s law: At fixed temperature and pressure, the volume of a gas is directly proportional to the amount of gas. V α n V = cn V/n = c V 1 /n 1 = V 2 /n 2

© 2010 Pearson Prentice Hall, Inc. 6/22 The Gas Laws Standard temperature and pressure: Standard temperature = 0 o C Standard pressure = 1 atm A mole of any gas at STP occupies 22.4 L

© 2010 Pearson Prentice Hall, Inc. 6/23 The Gas Laws Combined gas law: P 1 V 1 = P 2 V 2 T 1 T 2

© 2010 Pearson Prentice Hall, Inc. 6/24 The Gas Laws Ideal gas law: PV = nRT R =