Solution
a) Step 1) Calculate the amount of sugar in mole.
1.08/180 =0.006
Step 2) calculate the energy given out by the burning of 1.08 grams of sugar.
Energy = mole X 2803KJ/mole
= 0.006 X 2803 =16.82KJ
Step 3) Calculate the calibration factor according to the expression below.
Energy/temperature change
= 16.82/1.05
=16.02KJ/°C
b) Step 1) The energy
given out is calculated by the expression below
Energy =calibration
factor X temperature change
= 16.02 X 3.0 = 48.3KJ
Step 2) The mole of hydrogen gas is calculated by
mass/formula mass = 0.4/2 = 0.2 mole
Step 3) Energy per mole of hydrogen gas
48.3 /0.2 = 241.5KJ/mol.
Click to hide the solution
|
Calorimetry
exercise 7 |
|
A 1.08gram sample
of pure glucose is burnt in a bomb calorimeter. The sugar sample was then
ignited in the presence of excess oxygen and the temperature of the water
in the calorimeter was observed to rise by 1.05°C. C = 12, O = 16, H =1 |
|
a) If the heat of combustion of glucose is 2803KJ/mole calculate the calibration factor of the calorimeter in KJ/°C. b) The same calorimeter was then used to determine the heat given out when 0.4grams of hydrogen was ignited in excess oxygen. Calculate the heat of combustion of hydrogen gas if the temperature was observed to rise by 3.0°C. Solution
|