# Enthalpy of Solution (HSOLN)

## Presentation on theme: "Enthalpy of Solution (HSOLN)"— Presentation transcript:

Enthalpy of Solution (HSOLN)

When substances dissolve in water, an energy change usually occurs.
Enthalpy of solution is defined as the enthalpy change when 1 mole of a substance completely dissolves (kJ mol-1)

Experiment 50cm3 of H2O Thermometer Balance 2g NaOH or 4g NH4NO3

Measurements Taken Volume (mass) of water Mass of substance dissolves
Temperature of water at start Temperature of water at end

Specimen Results 1.03g of NaOH was dissolved in 50g (0.05kg) of water. The temperature of water rose by 5oC. Calculate the enthalpy of solution of NaOH.

1. Calculate energy change
EH = c x m x ΔT = 4.18x0.05x5 = kJ 2. Calculate the number of moles of NaOH 1 mole NaOH=40g so 1.03g=1.03/40= mol 3. Calculate enthalpy of solution 0.026 moles: 1.045kJ 1 mole : 40.2kJ

Therefore the Enthalpy of solution= -40.2kJ
Note that HSOLN can be a +ve or –ve value. You can work out which it is from the question.