Liquids and Solids

Water

Objectives

1. Describe the structure of a water molecule.

2. Explain the physical properties of water in terms of the intermolecular forces that exist between molecules.

3. Calculate the amount of heat energy absorbed or released when a quantity of water changes state.

Structure of Water

• Polar bonds• sp3 hybridization• 105o bond angle• Hydrogen bonding

Structure of Water

Liquid

Solid

Structure of Water

Physical Properties of Water• Water has a high

melting (0oC) and boiling point (100oC)

Physical Properties of Water•Water has a high specific heat.•It can absorb or release large amounts of energy without its temperature changing significantly

Physical Properties of Water• Water has a high heat

of vaporization.

Physical Properties of Water• Liquid water becomes

less dense as it warms.• Ice is less dense than

liquid water.

Phase Changes

Molar Heat of Fusion

6.01 KJ/mol

Molar Heat of Vaporization

40.79 KJ/mol

Heat Calculations

1. What quantity of heat is released when 506 g of liquid water freezes?

2. What mass of steam is required to release 4.97 x 105 KJ of heat energy on condensation?

kJmol

kJ

OHg

OHmolOHg 169

1

009.6

0153.18

1506

2

22

gxOHmol

OHg

kJ

molkJx 5

2

25 1019.21

0153.18

79.40

11097.4