2. Updated Sept 2006Created by C. Ippolito Sept 2006 Temperature and Heat Objectives: 1.identify various forms of energy 2.describe energy changes during a chemical reaction 3.distinguish between heat energy and temperature 4.solve calorimetry problems

3. Updated Sept 2006Created by C. Ippolito Sept 2006 Temperature and Heat Energy Temperature measures the “hotness” and “coldness” of matter intensitymeasures the intensity of energy of the particles of a substance hot water cold waterhot water particles have more energy than cold water particles Heat form energy transferred between matter with different temperatures hot objectcold objectflows from the hot object to the cold object

4. Updated Sept 2006Created by C. Ippolito Sept 2006 Heat Energy and Temperature Celsius ScaleCelsius Scale Anders Celsius 0 o C water freezes 100 o C water boils Kelvin scaleKelvin scale William Kelvin Based on theoretically lowest temperature of absolute zero where all molecular motion stops

5. Updated Sept 2006Created by C. Ippolito Sept 2006 Temperature Conversions To convert Celsius to Kelvin Add 273 to Celsius temperature 50 o C = ? K 50 o C + 273 = 323 K To convert Kelvin to Celsius Subtract 273 from Kelvin temperature 30 K = ? o C 30 K – 273 = -243 o C

6. Updated Sept 2006Created by C. Ippolito Sept 2006 Heat Energy Units joule SI unit of heat energy calorie familiar metric unit of heat energy energy needed to raise 1 g of water 1 o C Calorie larger metric unit used with food 1 Calorie = 1000 calories = 1 kilocalorie relationship between calorie – joule 1 calorie = 4.184 joules

7. Updated Sept 2006Created by C. Ippolito Sept 2006 Heat Measurement Calorimeter used to measure heat by rise or fall of temperature of water Specific Heat Capacity (C P ) amount of joules needed to raise 1g of a substance 1 o C measured as listed on page 67 C P water = 4.184 J/g  o C C P aluminum = 0.900 J/g  o C

8. Updated Sept 2006Created by C. Ippolito Sept 2006 Heat Calculations Equation: Heat transferred = m   T  C P water M = mass of water  T = change in water temperature C Pwater = 4.18 J/g  o C How much energy is needed to raise 40 g of water from 20.0 o C to 36 o C? Known: C Pwater = 4.18 J/g  o C T initial = 20 o C T final = 36 o C m = 40 g Unknown: Heat transferred

9. Updated Sept 2006Created by C. Ippolito Sept 2006 Heat Calculations (con’t) How much heat energy is lost when a solid ingot of aluminum with a mass of 4 110 g cools from 660 o C to 25.0 o C? Known: C Paluminum = 0.903 J/g  o C T initial = 660 o C T final = 25.0 o C m = 4 110 g Unknown: Heat transferred