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Calorimetry
Since we cannot know the exact enthalpy of the reactants and products, we measure H through calorimetry, the measurement of heat flow.
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2. Heat Capacity and Specific Heat
The amount of energy required to raise the temperature of a substance by 1 K (1C) is its heat capacity.
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3. Heat Capacity and Specific Heat
Specific heat, then, is
Specific heat =
heat transferred
mass  temperature change
c = q
m  T
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4. Constant Pressure Calorimetry
By carrying out a reaction in aqueous solution in a simple calorimeter such as this one, one can indirectly measure the heat change for the system by measuring the heat change for the water in the calorimeter.
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5. Constant Pressure Calorimetry
Because the specific heat for water is well known (4.184 J/g-K), we can measure H for the reaction with this equation:
q = m  c  T
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6. Important calorimetry lab data
Your task will be to accurately find the specific heat of a sample of metal
Data to collect: mass of water, mass of metal, starting temperature of metal and water, ending temperature of metal and water
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It’s important to:
Let the metal sit in boiling water for several minutes to reach max temp
Transfer the metal quickly to the water (in a cup)
Allow the water to reach max temp (swirl the cup) then use that temp as your final
Remember to collect data before you start
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After the lab
Find the specific heat of the metal
Do error analysis to see how close you were to the known specific heat
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9. The key to understanding calorimetry
The heat lost by the metal must be equal to the heat gained by the water.
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Lab Practice
Data for water: m = 120.2g c = ? Starting temp = 22.1C final temp = 25.8C
Data for metal m = 62.4g
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