Determination of Enthalpy of Solution of Oxalic Acid

22nd Nov 2024

Experiment 14

Objective

To determine the enthalpy of solution of oxalic acid.

Introduction

The enthalpy of solution refers to the heat change when 1 mole or 1 gram of solute dissolves in a solvent. For oxalic acid, when 12.6 g dissolves in water, the enthalpy change can be calculated from the observed temperature difference.

●       Molecular weight of oxalic acid: 126 g/mol

●       Concentration for 0.1 M solution: 12.6 g in a sufficient amount of solvent to make the solution 0.1 M.

Materials

Chemicals

●      Oxalic acid

●      Distilled water

Apparatus

●      250 mL beaker

●      Glass rod

●      Thermometer

●      Stand

●      Balance

Reagents

●      12.6 g oxalic acid and 87.4 g distilled water in a 250 mL beaker.

Procedure

1.    Weigh 12.6 g of oxalic acid using a balance.

2.    Place the oxalic acid in a 250 mL beaker.

3.    Suspend a thermometer in the beaker using a stand and record the initial temperature.

4.    Add distilled water to the beaker containing oxalic acid.

5.    Wait 2–3 minutes for the temperature to stabilize.

6.    Stir the solution with a glass rod to ensure complete dissolution of the oxalic acid.

7.    Record the final temperature of the solution.

Observation

The initial temperature of the solution is 29.46°C, and the final temperature after dissolution is 25.18°C.

Enthalpy of Solution Calculation:

Enthalpy of solution= 0.42 × (29.46−25.18) × 10kJ/mol = + 17.98kJ/mol

Questions

1.    What is solution temperature?

2.    What is molarity?

3.    What is the enthalpy of oxalic acid?

4.    How is enthalpy measured?