Experiment -
Aim: To determine the integral enthalpy of solution of potassium nitrate in 1:200 mole ratio.
Apparatus: Thermos flask with its lid having two holes, 250 mL beakers, stirrer, 0.1oC
thermometer, tripod stand, wire gauze, stop watch, burner, standard flasks
Theory: Integral enthalpy of solution, ΔsolnH, is defined as the change in enthalpy when one mole
of the solute is dissolved in a specified amount (number of moles) of solvent at a constant
temperature and under a constant pressure. It corresponds to the process:
X (s) + n H2O(l) → X .nH2O (aq) ΔsolnH
where ΔsolnH is the integral enthalpy of solution of the solute X in water in 1 : n molar ratio. It is
observed that dissolution process for some solutes is exothermic while for others it is
endothermic.
Procedure: This experiment was performed in the following two steps.
I. Determination of heat capacity of calorimeter:
Same as experiment __
Calculation of the mass of KNO3 required for preparing a solution in 200 mL water in
which its molar ratio is 1:200.
Mass of water to be used = 200 g
Molar mass of KNO3 = 101 g mol-1
Molar mass of water = 18 g mol-1
Mass of 200 moles of water = 200 x 18 g
Mass of KNO3 to be dissolved in 200 x 18 g water = 101 g
200× 101
Mass of KNO3 to be dissolved in 200 g water = = ____ g
200× 18
II. Determination of Enthalpy of Solution
1. Same set of thermometer and thermos flask were used in this step.
2. The predetermined amount of the KNO3 was weighed.
3. 200 mL of distilled water was taken in the thermos flask with the help of standard
flask.
4. The thermometer was dipped in it and the lid of the flask closed tightly.
5. The stop watch was started and the temperature of water in the calorimeter was
noted for 3.5 minutes at an interval of 30 seconds.
6. KNO3 was added to water carefully noting down the time of mixing.
Aim: To determine the integral enthalpy of solution of potassium nitrate in 1:200 mole ratio.
Apparatus: Thermos flask with its lid having two holes, 250 mL beakers, stirrer, 0.1oC
thermometer, tripod stand, wire gauze, stop watch, burner, standard flasks
Theory: Integral enthalpy of solution, ΔsolnH, is defined as the change in enthalpy when one mole
of the solute is dissolved in a specified amount (number of moles) of solvent at a constant
temperature and under a constant pressure. It corresponds to the process:
X (s) + n H2O(l) → X .nH2O (aq) ΔsolnH
where ΔsolnH is the integral enthalpy of solution of the solute X in water in 1 : n molar ratio. It is
observed that dissolution process for some solutes is exothermic while for others it is
endothermic.
Procedure: This experiment was performed in the following two steps.
I. Determination of heat capacity of calorimeter:
Same as experiment __
Calculation of the mass of KNO3 required for preparing a solution in 200 mL water in
which its molar ratio is 1:200.
Mass of water to be used = 200 g
Molar mass of KNO3 = 101 g mol-1
Molar mass of water = 18 g mol-1
Mass of 200 moles of water = 200 x 18 g
Mass of KNO3 to be dissolved in 200 x 18 g water = 101 g
200× 101
Mass of KNO3 to be dissolved in 200 g water = = ____ g
200× 18
II. Determination of Enthalpy of Solution
1. Same set of thermometer and thermos flask were used in this step.
2. The predetermined amount of the KNO3 was weighed.
3. 200 mL of distilled water was taken in the thermos flask with the help of standard
flask.
4. The thermometer was dipped in it and the lid of the flask closed tightly.
5. The stop watch was started and the temperature of water in the calorimeter was
noted for 3.5 minutes at an interval of 30 seconds.
6. KNO3 was added to water carefully noting down the time of mixing.
