CBSE Class 11 chemistry · volumetric analysis · Volumetric analysis

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

Titration of HCl with sodium carbonate (Class 11 chemistry practical)

You titrate the given HCl against pipetted standard Na₂CO₃ (or the reverse if your manual says so).

Concentrations and volumes are manual-driven.

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.

HCl is corrosive and produces irritating fumes.
Wear goggles and gloves; wipe acid spills as your teacher directs.

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 molarity (strength) of the given hydrochloric acid by titrating against the standard sodium carbonate solution from your laboratory manual.

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

Apparatus and chemicals

Apparatus and chemicals
Item	Note
Burette and stand	HCl or Na₂CO₃ placement as manual.
Pipette	Rinse with solution you pipette.
Conical flask	Distilled water rinse only.
Methyl orange indicator	Yellow to pink/red end point in acid medium.
White tile	End-point visibility.
Hydrochloric acid (unknown) (HCl)	Use the concentration, mass, volume, and sample names printed in your school laboratory manual. This page does not invent numerical results for you.
Standard Na₂CO₃ (Na2CO3)	Use the concentration, mass, volume, and sample names printed in your school laboratory manual. This page does not invent numerical results for you.
Methyl orange (methyl orange)	Few drops.

Burette and conical flask set up for titration — Read the burette at eye level. The end-point colour in a diagram is only a guide — your titre is the volume you measure.

Theory and reaction

Open

Na₂CO₃ + 2HCl → 2NaCl + H₂O + CO₂. Methyl orange end point marks completion to acidic products.

Effervescence may be seen — swirl gently.

Calculate HCl molarity from pipette volume of carbonate, known carbonate molarity, and titre volume of acid.

Carbonate neutralised by two equivalents HCl at methyl orange end point.

Procedure

Fill burette with HCl after rinse. Record initial reading.
Pipette Na₂CO₃ into flask. Add methyl orange.
Titrate until colour changes from yellow to the pink/orange end point your manual describes.
Repeat for concordant titres.
Calculate HCl molarity using 2:1 HCl:Na₂CO₃ mole ratio.

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

S. No.	Initial reading (mL)	Final reading (mL)	Volume of HCl used (mL)
1
2
3

Calculation

n(HCl) = 2 × n(Na₂CO₃) for pipetted carbonate. M(HCl) = moles / titre volume in L.

Result

State HCl molarity from your concordant readings.

Precautions

HCl fumes — ventilation.
CO₂ bubbles: swirl, do not shake violently.
Methyl orange choice matches strong acid–weak base salt titration curve region.

Viva questions

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

Question 1 of 4

Methyl orange is preferred here because…

A. It works in strong base onlyB. End point is in acidic pH range matching complete reaction with carbonateC. It is a primary standardD. It replaces HCl

Pick an answer first.

Show all questions and answers

Methyl orange is preferred here because…
Answer: End point is in acidic pH range matching complete reaction with carbonate. Reason: Carbonate titration to CO₂ needs acidic end point.
Gas evolved during titration is…
Answer: CO₂. Reason: Carbonate + acid produces carbon dioxide.
If you pipette Na₂CO₃, the burette typically holds…
Answer: HCl of unknown strength. Reason: Unknown acid titrated against known carbonate.
Rinsing the conical flask with distilled water before titration…
Answer: Does not change moles already delivered by pipette. Reason: Pipette fixes moles; extra water dilutes but does not change mole count.

Common mistakes

Using phenolphthalein when manual specifies methyl orange for complete reaction.
1:1 mole ratio error.
Over-titrating past sharp end point.

Frequently asked questions

Can I do this at home?: No. Use this page to practise the order of steps and viva. 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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