(2) How to Determine the Heat of Neutralization | Problems and Solutions

To complete a lab involving the heat of neutralization, follow these general steps:

  1. Gather Materials:

    • Acid and base solutions (e.g., hydrochloric acid and sodium hydroxide)

    • Glass calorimeter

    • Thermometer

    • Measuring cylinders

    • Balance to measure mass

    • Pipettes

  2. Prepare Solutions:

    • Measure and add a known volume of acid to the calorimeter.

    • Measure and add a known volume of base to a separate container.

  3. Measure Initial Temperature:

    • Use the thermometer to measure and record the initial temperature of both the acid and the base solutions (T1).

  4. Mix the Solutions:

    • Quickly pour the base into the acid in the calorimeter and stir gently to ensure thorough mixing.

  5. Measure Final Temperature:

    • After mixing, monitor the temperature change until it stabilizes, then record the maximum final temperature (T2).

  6. Calculate Temperature Change:

    • Determine the change in temperature (ΔT = T2 - T1).

  7. Calculate Heat Released (Q):

    • Use the formula: Q = Ms × Cs × ΔT, where:

      • Ms = mass of the solution mixture (add the volumes of acid and base and multiply by the density to convert from volume to mass if necessary)

      • Cs = specific heat capacity of the solution (use approximate value if not known)

  8. Calculate Moles of Acid/Base:

    • Use the molar concentration and volume measurements to determine the number of moles (N) of the limiting reactant.

  9. Calculate ΔH°:

    • Apply the formula: ΔH° = -Q / N to find the heat of neutralization per mole.

  10. Analyze and Report Results:

  • Compare results with theoretical values (e.g., -57.1 kJ/mol for strong acids/bases) and discuss any discrepancies.

  1. Clean Up:

  • Dispose of the reagents properly and clean your equipment.