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Class 11 chemistry · linked to Thermodynamics basics · Physical chemistry experiments

Source: CBSE Class 11 chemistry practical syllabus · use your school laboratory manual (NCERT Lab Manual where your school uses it).

Enthalpy of neutralisation (Class 11 chemistry practical)

You mix acid and base in an insulated cup and track temperature change.

Volumes, molarities, and the calorimeter constant (if used) come from your manual.

Published practice page. Concentrations, masses, and numerical answers come from your school laboratory manual and your own readings — not invented here. Not yet reviewed by a named chemistry reviewer. Version 1.0.0, updated 2026-10-03.

Safety — read before you start

Safety warning. Practise here. Perform the real experiment only in your school lab, with your teacher present.

  • Dilute acids and bases still burn skin and eyes.
  • Broken thermometers may contain hazardous fillings — handle as taught.

Wear: Lab coat, Splash goggles, Gloves, as your teacher directs.

Follow your teacher’s disposal instructions. Do not pour leftovers down a household drain.

Loads only after you tap. Use the lab hands to pick up and use equipment (pointer hidden in the scene). Falls back to a flat diagram if WebGL is unavailable.

Aim

To determine the enthalpy of neutralisation for the acid–base pair in your laboratory manual using a simple calorimeter, without copying a pre-filled ΔH from elsewhere.

Methods and quantities can differ between schools. Follow your teacher's instructions.

Apparatus and chemicals

Apparatus and chemicals
ItemNote
Polystyrene / school calorimeterLid with hole for the thermometer.
ThermometerResolution as per manual.
Measuring cylinder or pipetteFor the volumes your manual states.
Glass rodGentle stir — do not break the thermometer bulb.
Strong acid solution (acid)Use the concentration in your laboratory manual.
Strong base solution (base)Use the concentration in your laboratory manual.
Calorimeter cup with thermometer for acid–base mix
Note T₁ before mixing, then T₂ after. ΔT and ΔH come from your thermometer and your manual’s formula — not from this photo.

Theory and reaction

Open

At constant pressure, heat released ≈ q_p related to ΔH.

q = m c ΔT for the solution (and calorimeter term if your manual includes it).

For strong acid + strong base, the essential reaction is H+ + OH- → H2O. Weak acids/bases need extra dissociation heat — your manual will say which pair you have.

H+ plus OH- gives water.

Procedure

  1. Measure the acid volume your manual states into the calorimeter. Record initial temperature.
  2. Measure the base the same way. Record its temperature if the manual asks for a separate reading.Safety: Acids and bases are corrosive. Wipe spills as your teacher shows.
  3. Mix quickly, lid on, stir gently. Record the highest (or stable) temperature your manual asks for.
  4. Compute ΔT and q using only the formula and constants in your manual.
  5. Report ΔH per mole of water formed (or as the manual defines the basis).

Observation table

Enter the readings from your school lab in the practical file below. This page does not fill them in for you.

Type the readings in your practical file

Calculation

Use q = m c ΔT (and calorimeter correction if given). Divide by moles of limiting reagent / water as your manual defines. No sample arithmetic with invented numbers here.

Result

Write ΔH with sign and unit (kJ mol⁻¹) from your own temperatures.

Precautions

  • Read the thermometer at eye level.
  • Mix promptly so heat is not lost before you record T.
  • Do not use a glass beaker as if it were a perfect insulator unless that is the school method.

Viva questions

Answer one question at a time. The full answers stay closed until you open them.

Question 1 of 3

ΔH for an exothermic neutralisation is usually…

Answer choices

Pick an answer first.

Show all questions and answers

  1. ΔH for an exothermic neutralisation is usually…

    Answer: Negative. Reason: Heat leaves the system; ΔH is negative by convention.

  2. q at constant pressure corresponds to…

    Answer: ΔH. Reason: q_p = ΔH.

  3. Hess’s law says overall ΔH…

    Answer: Is path-independent for the same start/end. Reason: State function behaviour for enthalpy.

Common mistakes

  • Forgetting the sign (exothermic ⇒ negative ΔH in the usual chemistry convention).
  • Using mass of only one solution when the manual says to add both masses.
  • Copying −57.1 kJ mol⁻¹ into the file without measuring.

Frequently asked questions

Can I do this at home?
No. Use this page to practise the order of ideas and steps. Do the real experiment only in your school laboratory, with your teacher present.

Your practical file

Name, school, and roll number are optional and are not sent anywhere.

The practical file opens on this device.

Review

Not yet reviewed by a named chemistry reviewer. Published for practice only — follow your teacher and laboratory manual for quantities and safety.

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Related notes

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