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Enthalpy of Neutralization Calorimetry: Strong Acid & Strong Base

Experiment video

What you will learn

Determine the enthalpy of neutralization of a strong acid (1.0 M HCl) with a strong base (1.0 M NaOH) using a polystyrene coffee cup calorimeter.

Materials needed

1.0 M Hydrochloric Acid (HCl) solution mL
1.0 M Hydrochloric Acid (HCl) solution mL
₹50
What is it?
Vacuum-jacketed silvered glass Dewar calorimeter flask mounted in protective wooden case with cork lid.
Specifications
Capacity
500 mL
Thermal Leakage Rate
< 0.05 °C/min
Lid Fittings
Holes for thermometer and wire stirrer
Insulation
High vacuum silvered double-wall Dewar
1.0 M Sodium Hydroxide (NaOH) solution mL
1.0 M Sodium Hydroxide (NaOH) solution mL
₹95
What is it?
High-precision 1/10th degree laboratory thermometer.
Specifications
Range
0 to 50 °C
Graduation
0.1 °C divisions
Accuracy
± 0.05 °C calibrated
Filling
Non-toxic organic blue liquid with white backing
Expanded Polystyrene (Styrofoam) Cup Calorimeter with lid
Expanded Polystyrene (Styrofoam) Cup Calorimeter with lid
₹140
What is it?
Standardized 1.00 M Hydrochloric Acid and 1.00 M Sodium Hydroxide volumetric solutions.
Specifications
Concentration
1.000 M ± 0.005 M
Purity
AR Analytical Reagent grade
Volume
500 mL each bottle
Specific Heat
c = 4.184 J/g°C
Precision Beckman/Digital Thermometer (0.01°C least count)
Precision Beckman/Digital Thermometer (0.01°C least count)
₹185
What is it?
Standard laboratory apparatus used in Enthalpy of Neutralization Calorimetry: Strong Acid & Strong Base.
Specifications
Category
Chemistry Apparatus
Grade
CBSE / NEP 2020 Laboratory Standard
Calorimeter Plastic Stirrer
Calorimeter Plastic Stirrer
₹230
What is it?
Standard laboratory apparatus used in Enthalpy of Neutralization Calorimetry: Strong Acid & Strong Base.
Specifications
Category
Chemistry Apparatus
Grade
CBSE / NEP 2020 Laboratory Standard
Graduated Cylinders (100 mL)
Graduated Cylinders (100 mL)
₹275
What is it?
Standard laboratory apparatus used in Enthalpy of Neutralization Calorimetry: Strong Acid & Strong Base.
Specifications
Category
Chemistry Apparatus
Grade
CBSE / NEP 2020 Laboratory Standard
Distilled water wash bottle
Distilled water wash bottle
₹320
What is it?
Standard laboratory apparatus used in Enthalpy of Neutralization Calorimetry: Strong Acid & Strong Base.
Specifications
Category
Chemistry Apparatus
Grade
CBSE / NEP 2020 Laboratory Standard

Tick items as you collect them. Tap + to see the product, specifications and buy options.

Stay safe

Mix acid and base rapidly without splashing to minimize early heat dissipation.
Stir gently and constantly to maintain uniform thermal equilibrium throughout the mixture.
Ensure thermometer bulb is fully submerged in the liquid without touching the cup bottom or walls.
Keep calorimeter cover tightly seated to avoid convective heat losses.

Steps

0 of 7 steps done

1Determine calorimeter water equivalent (W) using hot and cold water mixing method.
Observation
Determine water equivalent W of polished vacuum Dewar flask calorimeter using warm water mixing method (W = 40 J/°C).
Safety
Inspect thermos glass liner for cracks before mounting in wooden housing.
2Measure exactly 100 mL of 1.0 M HCl in a graduated cylinder and transfer to the calorimeter cup.
Observation
Measure exactly 100 mL of 1.0 M HCl into clean calorimeter; record steady baseline temperature T1 = 24.2 °C.
Safety
Use 0.1°C precision Beckman or digital thermometer; do not bump bulb on calorimeter bottom.
3Measure exactly 100 mL of 1.0 M NaOH in another cylinder. Place both solutions side by side until both reach the exact same initial temperature (T1).
Observation
Measure exactly 100 mL of 1.0 M NaOH in separate beaker; ensure temperature T2 matches T1 within 0.1°C.
Safety
Rinse thermometer thoroughly between measuring acid and base.
4Record initial temperature T1 to 0.1°C precision.
Observation
Pour NaOH rapidly into calorimeter, seal lid immediately with rubber cork, and stir gently with plastic stirrer.
Safety
Pour quickly without splashing; seal immediately to minimize evaporative heat loss.
5Pour the 100 mL NaOH quickly into the calorimeter cup containing HCl.
Observation
Record temperature every 15 seconds; temperature peaks rapidly at T_max = 30.7 °C (ΔT = 6.5 °C).
Safety
Stir with steady circular rhythm without excessive friction heating.
6Immediately replace the insulated lid, insert the thermometer and stirrer, and stir smoothly.
Observation
Calculate heat evolved Q = (m·c + W)·ΔT = (200 × 4.184 + 40) × 6.5 = 5700 J for 0.1 mol => ΔH = -57.0 kJ/mol.
Safety
Neutralized salt solution (pure 0.5M NaCl) is safe to wash down sink.
7Record the temperature every 15 seconds until it reaches a maximum peak (T2) and begins to fall. Calculate ΔH = -[m·c + W]·(T2 - T1) / n.

Tap + on a step to see what you will observe and any safety tips.

Record your observations

Calorimetric Parameter	Value / Reading	Units	Scientific Significance
Initial Temp of 1.0 M HCl (T1)	24.2 °C	Degrees Celsius	Ambient thermal equilibrium
Initial Temp of 1.0 M NaOH (T2)	24.2 °C	Degrees Celsius	Matched baseline temperature
Mean Initial Temperature (T_init)	24.2 °C	Degrees Celsius	T_init = (T1 + T2)/2
Maximum Neutralization Temp (T_max)	30.7 °C	Degrees Celsius	Peak exothermic reading
Temperature Rise (ΔT)	6.5 °C	Degrees Celsius	ΔT = T_max - T_init
Calculated Molar Enthalpy (ΔH_neut)	-57.0 kJ/mol	kJ per mole of H2O	Close to theoretical -57.3 kJ/mol

Tap a highlighted cell to write your own observation.

Result and conclusion

Temperature rise of 6.7°C measured. Heat released yields enthalpy of neutralization ΔH = -56.8 kJ/mol, matching theoretical standard thermodynamic value (-57.1 kJ/mol) within 0.7% error.

ΔH_neut = - (m · c + W) · ΔT / n = - (200 g × 4.184 J/g°C + 40 J/°C) × 6.5 °C / 0.100 mol = -57.0 kJ/mol

Observation	What it means
Exothermic Heat of Neutralization	Neutralization of strong acid by strong base (H⁺ + OH⁻ -> H2O) releases heat, raising solution temperature by 6.5 °C.
Theoretical Agreement	Experimental ΔH = -57.0 kJ/mol matches theoretical literature value -57.3 kJ/mol within 0.5% experimental error.
Calorimeter Water Equivalent	Incorporating the calorimeter water equivalent (W = 40 J/°C) accounts for heat absorbed by the thermos glass and thermometer.
Constancy for Strong Pairs	Any strong acid - strong base pair gives essentially identical ΔH (~ -57.3 kJ/mol) because the net reaction is purely water formation.

Calorimeter Temperature vs Time (Cooling Curve Extrapolation)

Sample readings. Replace with your own results.

Experiment photos

Before the experimentDuring the experimentResult