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).

Standard sodium carbonate solution (Class 11 chemistry practical)

Anhydrous sodium carbonate is a common primary standard for preparing a base solution to standardise acids in school.

Mass, molarity, and flask volume 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.

Irritant dust — avoid inhaling.
Broken glass.

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

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

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Aim

To prepare a standard solution of sodium carbonate of the strength specified in your laboratory manual.

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

Apparatus and chemicals

Apparatus and chemicals
Item	Note
Volumetric flask	Use the concentration, mass, volume, and sample names printed in your school laboratory manual. This page does not invent numerical results for you.
Balance and watch glass	Weigh anhydrous or dried salt as directed.
Beaker and funnel	Dissolve before transfer.
Wash bottle	Distilled water.
Sodium carbonate (anhydrous or as manual) (Na2CO3)	Use the concentration, mass, volume, and sample names printed in your school laboratory manual. This page does not invent numerical results for you.
Distilled water (H2O)	Solvent.

Volumetric flask with calibration mark and meniscus — Make up to the mark after the solid has dissolved. Read the meniscus at eye level so the curve sits on the line.

Theory and reaction

Open

Na₂CO₃ is a primary standard when dry. It reacts with strong acid in two stages; for school titration to methyl orange end point, the overall reaction is treated as Na₂CO₃ + 2HCl → 2NaCl + H₂O + CO₂.

Molarity from weighed mass and flask volume.

One mole carbonate reacts with two moles HCl to methyl orange end point.

Procedure

Weigh the mass of Na₂CO₃ calculated from manual molarity and volume.
Dissolve in distilled water in a beaker. Transfer to volumetric flask with rinses.
Make up to the mark. Mix well.
Label the flask.

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.	Mass of Na₂CO₃ (g)	Flask volume (mL)	Target molarity (mol L⁻¹)
1
2
3

Calculation

mass = M × V(L) × molar mass of Na₂CO₃ (anhydrous unless manual states otherwise).

Result

Record mass weighed and intended molarity.

Precautions

Use dried carbonate if manual warns about water of crystallisation.
CO₂ evolution on titration is normal — not in this preparation step.
Meniscus reading at eye level.

Viva questions

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

Question 1 of 4

Sodium carbonate is used as…

A. An oxidising agent onlyB. A primary standard base for preparing standard solutionC. A gasD. Indicator

Pick an answer first.

Show all questions and answers

Sodium carbonate is used as…
Answer: A primary standard base for preparing standard solution. Reason: Standard base for acidimetry in schools.
Overall with methyl orange, 1 mol Na₂CO₃ needs…
Answer: 2 mol HCl. Reason: Two protons per carbonate for complete reaction to CO₂.
Why might Na₂CO₃ be dried before weighing?
Answer: To remove moisture that would lower effective mass of pure Na₂CO₃. Reason: Moisture error affects calculated molarity.
Distilled water is used because…
Answer: It avoids ions that interfere with a standard solution. Reason: Known solvent without extra ions.

Common mistakes

Using Na₂CO₃·10H₂O molar mass when manual expects anhydrous.
Incomplete dissolution before make-up.

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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