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 NaOH with oxalic acid (Class 11 chemistry practical)

You run oxalic acid from the burette (or pipette acid and titrate with NaOH — follow your manual’s arrangement) until the indicator end point.

Many manuals pipette oxalic acid and titrate with NaOH from the burette; use the layout your teacher assigns.

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.

NaOH corrosive.
Do not pipette by mouth.

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 strength of the given sodium hydroxide solution by titrating against the standard oxalic acid solution prepared as in 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	Usually filled with NaOH if acid is pipetted.
Pipette (25 mL typical)	Rinse with oxalic acid solution.
Conical flask	Rinse with distilled water only.
Funnel and white tile	For filling and end-point viewing.
Phenolphthalein indicator	Few drops as manual states.
Standard oxalic acid (H2C2O4)	Use the concentration, mass, volume, and sample names printed in your school laboratory manual. This page does not invent numerical results for you.
Sodium hydroxide solution (NaOH)	In burette or as manual arranges.
Phenolphthalein (phenolphthalein)	Pink in base, colourless in acid.

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

Neutralisation: H₂C₂O₄ + 2NaOH → Na₂C₂O₄ + 2H₂O.

Mole ratio 1 : 2 (acid : base). Phenolphthalein end point: first permanent faint pink from excess base (if titrating acid into alkali the colour change reverses — follow your manual).

Concordant titre volumes are averaged for calculation.

One mole oxalic acid reacts with two moles NaOH.

Procedure

Rinse and fill the burette with NaOH (or oxalic acid if manual reverses roles). Remove air bubble; record initial reading.
Pipette the standard oxalic acid volume into a conical flask. Add phenolphthalein.
Titrate with continuous swirling until a faint permanent pink end point (exact description as manual).
Record final burette reading. Repeat until concordant.
Calculate NaOH molarity using the 1:2 mole ratio and manual oxalic acid concentration.

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 used (mL)
1
2
3

Calculation

Use n(NaOH) = 2 × n(H₂C₂O₄) for the pipetted acid volume and known acid molarity. M(NaOH) = moles NaOH / volume NaOH in litres. Your manual may use normality — stay consistent.

Result

Write the molarity of NaOH from your concordant titres, with units mol L⁻¹.

Precautions

NaOH is corrosive — gloves and goggles.
Remove funnel before reading burette.
Swirl throughout; do not splash.
Phenolphthalein: do not confuse first flash of pink with end point.

Viva questions

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

Question 1 of 4

Phenolphthalein in this titration is…

A. A catalystB. An acid–base indicatorC. A primary standardD. The solvent

Pick an answer first.

Show all questions and answers

Phenolphthalein in this titration is…
Answer: An acid–base indicator. Reason: Indicator marks the end point by colour change.
Mole ratio of H₂C₂O₄ to NaOH in the balanced equation is…
Answer: 1:2. Reason: Diprotic acid needs two OH⁻ per mole.
Why rinse the pipette with oxalic acid solution?
Answer: So the delivered volume is the correct concentration. Reason: Removes water that would dilute the pipetted acid.
Concordant titre readings are…
Answer: Closely agreeing volumes used in calculation. Reason: Repeat until agreement within teacher’s limit.

Common mistakes

Using 1:1 mole ratio instead of 1:2.
Rinsing pipette with water only after oxalic acid rinse is skipped.
Reporting non-concordant readings.

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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