Enthalpy of Solution

1. When a substance is dissolved in 200 cm³ of water, the temperature rose from 18 ^oC to 23 ^oC. What is the energy change for this reaction?

2. When a substance was dissolved in 150 cm³ of water, the temperature fell from 22.5 ^oC to 18.1^oC. What was the energy change for this reaction?

3. A substance dissolved in 500 cm³ water and the temperature fell from 20.3 ^oC to 16.9^oC. What was the energy change for this reaction?

4. 0.01 moles of a substance was dissolved in 200 cm³ of water and the temperature dropped form 19 ^oC to 17 ^oC. What is the enthalpy of solution of this substance?

5. 0.025 moles of a salt dissolved in 400 cm³ of water and the temperature of the solution rose from 20 ^oC to 25 ^oC. What is the enthalpy of solution of this salt?

6. 0.05 moles of a compound dissolved in 500 cm³ of water, causing the temperature of the water to fall from 21 ^oC to 19.3 ^oC. What is the enthalpy of solution of the compound?

7. 5.3g of sodium carbonate (Na₂CO₃) was dissolved in 100 cm³ of water. The temperature of the water rose from 20.5 ^oC to 25.3 ^oC. What is the enthalpy of solution of this compound?

8. 14.92g of potassium chloride (KCl) dissolved in 250 cm³ of water causing the temperature of the water to change form 20.5 ^oC to 18.9 ^oC. What is the enthalpy of solution of potassium chloride?

9. 2.022g of potassium nitrate (KNO₃) is dissolved in 100 cm³ of water. The temperature of the water changed from 23.5 ^oC to 21.2 ^oC. What is the enthalpy of solution of potassium nitrate?

10. 8g of ammonium nitrate (NH₄NO₃) is dissolved in 200 cm³ of water causing the temperature to change from 17 ^oC to 14 ^oC. What is the enthalpy of solution of ammonium nitrate?

11. 4g of sodium hydroxide (NaOH) dissolved in 250 cm³ of water causing a temperature change from 19 ^oC to 23.3 ^oC. What is the enthalpy of solution of sodium hydroxide?

12. When 11.9g of potassium bromide (KBr) was dissolved in 300 cm³ of water the temperature changed from 24.8 ^oC to 21.2 ^oC. What was the enthalpy of solution?

13.      A student found that 1·08kJ of energy was released when 1·2 g of potassium hydroxide was dissolved completely in water.

Calculate the enthalpy of solution of potassium hydroxide.

14. Calculate the enthalpy change for each of the following experiments.

(a) When 1 g of potassium carbonate dissolved in 10 cm³ of water the temperature increased by 5.6⁰C.

(b) When 1 g of sodium nitrate dissolved in 10 cm³ of water the temperature fell by 5.6⁰C.

15. From the results of question 14 calculate the enthalpy of solution for

            a)  potassium carbonate (14a)

            b)  sodium nitrate (14b)

16.      The enthalpy change when 1 mole of sodium carbonate dissolves in water is 24.6 kJ mol^-1. Calculate the mass of sodium carbonate which would produce a temperature rise of 9.2⁰C             when added to 25cm³ of water.

17.      2g of sodium hydroxide, NaOH, is dissolved in 0.125 kg  of water causing the temperature to rise from 19^oC to 23^oC.            Calculate the enthalpy of solution of sodium hydroxide.

18.      14.9g of potassium chloride, KCl, is dissolved in 200cm³ of water causing the temperature to fall from 19.5^oC to 15.5^oC. Calculate the enthalpy of solution of potassium chloride.