Experiment 12

Objective

To determine the enthalpy of neutralization between hydrochloric acid (HCl) and potassium hydroxide (KOH), both strong acid and base.

Introduction

In an acid-base reaction, 1 mole of hydrogen ions is neutralized by a base, releasing heat, known as the enthalpy of neutralization. This reaction is exergonic, meaning it releases energy. The enthalpy of neutralization for all strong acids and bases is typically consistent.

Reaction:

HCl + KOH → KCl + H2​O

The enthalpy of neutralization for this reaction is calculated as:

ΔH = 0.42 × (Tfinal ​− Tinitial​) × 10kJ/mol

Materials

Chemicals

·       Hydrochloric acid (HCl, 2N)

·       Potassium hydroxide (KOH, 2N)

Apparatus:

·       250 mL beaker

·       Glass rod

·       Thermometer

·       Stand

·       Balance

Procedure

1.    Place 50 mL of 2N HCl in a 250 mL beaker.

2.    Secure the thermometer in the beaker using a stand.

3.    Record the initial temperature of the HCl solution.

4.    Add 50 mL of 2N KOH to the beaker with the HCl.

5.    Stir the mixture with a glass rod to ensure even mixing.

6.    Record the final temperature after the reaction is complete.

Observation

The initial temperature of the solution is 24°C, and the final temperature is 37°C.

Enthalpy of Neutralization Calculation

ΔH = 0.42 × (37−24) × 10kJ / mol =−54.6kJ / mol

Questions

1.    What is acid-base neutralization?

2.    What is the enthalpy of neutralization?

3.    How is enthalpy of neutralization determined?