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Unformatted text preview: Click to edit Master subtitle style We measure quantities of Heat using a Calorimeter . What we actually measure are masses and temperature changes. The Heat Capacity (C) of a system is the heat required to change the temperature of a system by 1 C (or 1 K). Molar Heat Capacity is the Heat Capacity of 1 mole of a substance, Specific Heat Capacity is the Heat Capacity of a 1g sample of the substance. C = q / T q = m specific heat capacty T We can carry out reactions at constant pressure in a Coffee Cup Calorimeter , and measure qp (which is the same as H). If we carry out reactions involving gases in a Bomb Calorimeter (which has a constant volume) we measure qv, (which is the same as U from U = q + w where w = PV). We could calculate H (which is more useful because our combustion reactions in the real world take place at constant P) from U (from H = U + PV), however in most reactions (except those involving large volumes of gases) PV is small, and so essentially H = U. reactions (except those involving large volumes of gases) PV is small, and so essentially H = U....
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- Spring '08