Experiment 13

Objective

To determine the enthalpy of neutralization between nitric acid (HNO₃) and sodium hydroxide (NaOH), 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 reactions involving strong acids and bases is typically consistent.

Reaction:

HNO3 ​+ NaOH → NaNO3 ​+ H2​O

The enthalpy of neutralization for this reaction is calculated as:

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

Materials

Chemicals

·       Nitric acid (HNO₃, 2N)

·       Sodium hydroxide (NaOH, 2N)

Apparatus

·       250 mL beaker

·       Glass rod

·       Thermometer

·       Stand

·       Balance

Procedure

1.    Place 50 mL of 2N HNO₃ in a 250 mL beaker.

2.    Secure the thermometer in the beaker using a stand and record the initial temperature.

3.    Add 50 mL of 2N NaOH to the beaker with HNO₃.

4.    Stir the mixture with a glass rod to ensure thorough mixing.

5.    Record the final temperature after the reaction completes.

Observation

The initial temperature of the solution is 23°C, and the final temperature is 37°C.

Enthalpy of Neutralization Calculation

ΔH= 0.42 × (37−23) × 10 kJ / mol = −58.8 kJ / mol

Questions

1.    What is acid-base neutralization?

2.    What is enthalpy of neutralization?

3.    How is enthalpy of neutralization determined?