1. Warm Up C 3 H 8 + O 2  CO 2 + H 2 O + 873kJ 1. How much energy is produced by the combustion of 31.0 grams of propane? 2. What mass of carbon dioxide would form when 2620kJ of energy is released? Hints: Equation must be balanced you are using molar ratios in these problems (energy is included in molar ratios)

2. And heat of fusion and vaporization

3. Specific heat capacity The amount of energy required to change the temperature of one gram of a substance by one Celsius degree is called its specific heat capacity, or more commonly, its specific heat. (pg 329) Q= C x m x ΔT Q= energy (heat) required C= specific heat capacity m= mass of sample in grams ΔT = change in temperature (celsius) final temp-initial temp

4. Example problems 1. Determine the amount of energy (heat) in joules required to raise the temperature of 1.5 moles of water from 29.0 o C to 46.0 o C. 2. What quantity of energy (in joules and calories) is required to heat a piece of iron weighing 1.3g from 25 o C to 46 o C? 3. A 1.6g sample of a metal that has the appearance of gold requires 5.8 J of energy to change its temperature from 23 o C to 41 o C. Is the metal pure gold?

5. Phase Change Diagram of water

6. Heat of fusion and Heat of vaporization It takes energy to melt ice and vaporize water, because intermolecular forces between water molecules must be overcome. Heat of fusion- the energy required to melt one mole of a solid Heat of vaporization- the energy required to vaporize one mole of a liquid

7. diagram The plateau at the boiling point is longer than the plateau at the melting point, because it takes almost seven times as much energy to vaporize liquid water as to melt ice. Hv water= 2260 J/g Hf water= 334 J/g