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# Specific Heat Capacity

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1. Specific Heat Capacity

2. Thermochemistry • deals with heat changes that occur during chemical reactions • Heat – reflection of amount of movement of mcs

3. Endothermic – heat flows into the system • the test tube gets cold – heat is absorbed • Exothermic – heat flows out of the system • the test tube gets hot – heat is given off

4. “Burning” calories • 1 calorie = quantity of heat needed to raise the temperature of 1 gram of water 1 oC • Calorie = dietary calorie = 1,000 calories = 1 kilocalorie • 1 Joule (metric unit) = 0.239 calories • 4.184 Joules = 1 calorie • 10 g of sugar = • 41 Calories of heat or • 41 kilocalories of heat

5. greater heat capacity greater heat capacity Heat Capacity • the amount of heat needed to increase the temperature of an object by 1 oC • depends on the mass and chemical composition of the matter iron block 250 gram steel cylinder 50 gram steel cylinder wooden block

6. Some specific heat capacities SubstanceJ/(gXoC) water 4.18 ice 2.1 aluminum 0.90 glass 0.50 iron 0.46 silver 0.24

7. Specific Heat Capacity • The amount of heat it takes to raise the temp. of 1 gram of a substance 1 oC • calorimetry = the measurement of heat changes

8. Calculation of the specific heat of a substance • S = specific heat • q = heat • m = mass • ∆T = change in temperature = T1 – T2 • S = ___q___ m X ∆T

9. Some problems! • The temperature of a piece of copper with a mass of 95.4 g increases from 25.0 oC to 48.0 oC when the metal absorbs 849 J of heat. What is the specific heat of copper? S = ___q___ m X ∆T m = 95.4 g ∆T = (48.0 oC – 25.0 oC) = 23.0 oC q = 849 J S = ______849J_______ 95.4 g X 23.0 oC = 0.387 J/g X oC

10. When 435 J of heat is added to 3.4 g of olive oil at 21 oC, the temperature increases to 85 oC. What is the specific heat of olive oil? S = ____435 J_____ 3.4 g X 64 oC S = 1.99 J/(gX oC)