### Altering the Volume of the Solution Without Altering the Concentration

If an experiment is repeated by alter the volume without alter the concentration, the temperature change will remain the same.**Example 1**:

When 50 cm³ of dilute hydrochloric acid 2 mol/dm³ is added into 50 cm³ of potassium hydroxide 2 mol/dm³, the temperature increase 13°C. What is the temperature increase if 300 cm³ of dilute hydrochloric acid 2 mol/dm³ is added into 300 cm³ of potassium hydroxide solution 2 mol/dm³ ?

**Answer**:

The volume of the reactants are increases by 6 times (300/50) whereas the concentration of the solution remain unchanged. Therefore the change of the temperature remain the same.

Temperature increase = 13°C

### Altering the Concentration of the Solution Without Altering the Volume

If an experiment is repeated by alter the concentration by n time without alter the volume of the solution, the temperature change will be n time of the initial temperature change as well.**Example 2**:

In an experiment, 50 cm³ of lead(II) nitrate solution 0.2 mol/dm³ is added into 50 cm³ of sodium carbonate solution 0.2 mol/dm³, the increase of temperature is 2.4°C. what is the increase in temperature if 50 cm³ of lead(II) nitrate solution 0.6 mol/dm³ is added into 50 cm³ of sodium carbonate solution 0.6 mol/dm³?

**Answer**:

The volume of the reactants remain unchanged whereas the concentration of the solution increases by 3 times (0.6/0.2). Therefore the change of the temperature

θ = 2.4°C x 3 = 7.2°C

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