Heat Capacity and Specific Heat
Heat capacity is the amount of energy required to
raise the temperature of an object by 1oC.
Molar heat capacity is the heat capacity of
1 mol of a substance.
Specific heat, or specific heat capacity is
the heat capacity of 1 g of a substance.
Heat, q = (specific heat) x (grams of substance) x T.
Calorimetry is a measurement of heat flow.
Calorimeter is an apparatus that measures heat flow.
Constant-Pressure Calorimetry
Most common technique: use atmospheric
pressure as the constant pressure.
Recall H = qp.
qsoln =(Specific Heat)SOLUTION x (grams) SOLUTION x T
To Raised 1gram of Water from 15.1 to 16.1 oC
Equals 4.184 J
DEFINED as 1 cal
Since we are using unit gram and temperature change,
qsoln is numerically equal to (Specific Heat)SOLUTION
Bomb Calorimetry (Constant-Volume Calorimetry)
Reactions can be carried out under conditions of
constant volume instead of constant pressure.
Constant volume calorimetry is carried out in a
bomb calorimeter.
The most common type of reaction studied under
these conditions is combustion.
If we know the heat capacity of the calorimeter,
Ccalorimeter, then the heat of reaction,
qrxn = –Ccalorimeter x T.
Since the reaction is carried out under constant
volume, q relates to E.