Heat Capacity _ Specific Heat

							Heat Capacity & Specific Heat

Heat Capacity
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the amount of heat required to raise the temperature of an object or substance by 1 K or (1°C) **The greater the heat capacity, the greater the heat required to produce a given increase in temp

Calorimetry & the Calorimeter
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Calorimetry – measurement of heat flow Calorimeter – device used to measure heat flow

Heat Capacity
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Molar Heat Capacity – the heat capacity for 1 mole of the substance Specific Heat Capacity (or Specific Heat) – heat capacity of 1 gram Can be written either way: Specific Heat – s Heat Capacity – c

Specific Heat
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Specific Heat = (quantity of heat transferred) (grams of subst) x (ΔT)

q = quantity of heat transferred m = mass s = specific heat s= q m x ΔT

ΔT
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ΔT in K = ΔT °C the difference in temp is the same

Water
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To raise 1 gram of water 1 °C it takes: 1 calorie = 4.184 J

Types of Calorimetry
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Constant – Pressure “Coffee cup” calorimetry qsoln = (specific heatsoln) x (gsoln) x (ΔT) = -qrxn

ΔT > 0 means exothermic, qrxn < 0

Types of Calorimetry
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Bomb Calorimetry – there is a sealed vessel that has a valve to allow the addition of O2 Heat is released when combustion occurs Heat is absorbed by calorimeter contents Temp is measured carefully before and after qrxn = -Ccal x ΔT Heat transferred corresponds to ΔE rather than ΔH, but they are very close, less 0.1%