Materials Required

• Calorimeter
• Thermometer
• Stirrer

Reagents

• HCl
• NaOH

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Procedure

Heat of Neutralisation

It is important to note that one should first select the sample “HCl” to proceed with the simulation. When the reading on the stopwatch reaches 4 minutes 30 seconds, you can then select the next sample “NaOH”.

When the reading of the NaOH sample also reaches 4 minutes 30 seconds, you can then select the final sample “HCl + NaOH”.

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1. Select HCl.
2. Start the reaction by clicking the “Start” button.
3. Note down the time and temperature up to 4 minutes 30 seconds.
4. Insert the values into the worksheet.
5. Find the constant temperature (T₂).
6. Enter the value into the worksheet.
7. Select NaOH (it will be active only after the above procedure).
8. Repeat steps 3–6 to obtain T₁.
9. Select the mixture “HCl + NaOH”.
10. Repeat steps 3–6 to obtain T₃.
11. Calculate the Heat of Neutralisation.

Note: It is assumed that at 4 minutes 30 seconds, the temperature of the calorimeter becomes a constant value.

Observations and Calculations

Heat of Neutralisation

Observed Values

• Temperature of alkali and calorimeter, T₁ = ______ °C
• Temperature of acid, T₂ = ______ °C
• Maximum temperature of mixture, T₃ = ______ °C
• Water equivalent of calorimeter, W = ______ cal/°C

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Calculation

Heat gained by solution and calorimeter:

Q = (50 + W)(T₃ − T₁) + 50(T₃ − T₂)

(Where 50 mL of each acid and base are used assuming density = 1 g/mL and specific heat = 1 cal/g°C.)

Q = ...................... cal

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Heat of Neutralisation:

ΔH = (Q × 1000) / (V × C)

Where:

• Q = Heat gained (cal)
• V = Volume of acid (or base) used in mL (typically 50 mL)
• C = Molarity of acid or base (mol/L)

ΔH = ...................... cal/mol = ...................... kJ/mol

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Results

Heat of Neutralisation of HCl with NaOH = ________ kJ/mol
(Expected theoretical value ≈ –57.3 kJ/mol)

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Precautions and Notes for Real Laboratory

• Always wear lab coat and gloves while handling chemicals.
• Switch on exhaust fan and ensure all reagents are ready before beginning.
• Use a proper Bunsen flame – small blue cone, not yellow/orange.
• Clean all glassware with chromic acid and rinse with distilled water.
• Calibrate the weighing balance before measuring.
• Close all reagent bottles after use and turn off gas, lights, and exhaust after the experiment.
• Discard gloves in the appropriate waste bin after use.