|AP Chemistry - Calorimetry Worksheet|
|1.||When sulphuric acid dissolves in water, a great deal of heat is
given off. The enthalpy change for this process is called the enthalpy
of solution. To measure it, 175 g of water was placed in a coffee-cup
calorimeter and chilled to 10oC. Then 49.0 g of pure sulphuric
acid, also at 10.0oC was added, and the mixture was quickly stirred
with a thermometer. The temperature rose rapidly to 14.9oC. Assume
that the value of the specific heat of solution is 4.184 J/goC.
You may assume that the specific heat of the resulting sulphuric acid solution
will also be 4.184 J/goC. Calculate q for the formation of this
solution, and calculate the enthalpy of solution in kilojoules per mole of
|2.||Gram for gram, fats in food have much more chemical energy than
sugar. One component of fat is stearic acid, C18H36O2.
When a sample of 1.02 g of stearic acid was burned completely in a bomb calorimeter,
the temperature of the calorimeter rose by 4.26oC. The heat capacity
of the calorimeter was 9.43 kJ/oC. Calculate the molar heat of
combustion of stearic acid in kilojoules per mole.
|3.||The reaction of 2.000 mol of gaseous hydrogen with 1.000 moles
of gaseous oxygen to form 2.00 mol of liquid water releases 517.8 kJ, provided
that all reactants and products are brought to 25oC and 1 at.
Write a thermochemical equation for the formation of 1.00 mol of liquid water.
|4.||Ethanol, C2H5OH, is made industrially by
the reaction of water with ethylene, C2H44. Calculate
the value of Ho for the reaction
C2H4(g) + H2O(l) ----> C2H5OH(l)
given the following thermochemical equations:
C2H4(g) + 3 O2(g) ----> 2 CO2(g) + 2 H2O(l) Ho = -1411.1 kJ
C2H5OH(l) + 3 O2(g) ---> 2 CO2(g) + 3 H2O(l) Ho = -1367.1 kJ