Volume strength of hydrogen peroxide: molarity, normality and % w/v

Set the volume strength of a hydrogen peroxide solution (10 volume, 20 volume ...) and see its molarity, normality, grams per litre, percentage w/v and the volume of oxygen it releases at STP. Free for every student.

Also searched as: volume strength of h2o2 · volume strength of h2o2 · 20 volume hydrogen peroxide · volume strength to molarity · normality of h2o2 · percentage w/v of h2o2

About this experiment

Aim

To understand what the volume strength of hydrogen peroxide means and to convert it to molarity, normality, grams per litre and percentage w/v.

Theory

Hydrogen peroxide decomposes to give oxygen: 2H₂O₂ → 2H₂O + O₂. Commercial solutions are labelled by their volume strength. A "20 volume" solution is one in which 1 mL of the solution gives 20 mL of oxygen measured at STP (0 °C and 1 atm).

From the equation, 2 mol of H₂O₂ (68 g) give 1 mol of O₂ (22.4 L at STP). So 1 L of an M molar solution contains M mol of H₂O₂ and gives M/2 × 22.4 = 11.2 M litres of oxygen. Hence the volume strength is V = 11.2 × M and the molarity is M = V / 11.2.

The equivalent mass of H₂O₂ is 17 (two electrons per molecule in this reaction, 34/2). The normality is N = 2M = V / 5.6. The strength in g/L is 34 × M, and the percentage w/v (grams in 100 mL) is that divided by 10. A 20 volume solution is about 1.79 M, 3.6 N, 60.7 g/L or 6.07 % w/v.

Formulas used

• 2 H₂O₂ → 2 H₂O + O₂
• volume strength V = 11.2 × M
• molarity M = V / 11.2
• normality N = V / 5.6
• strength (g/L) = 34 × M
• % w/v = strength (g/L) / 10
• O₂ from a sample = V × (volume of sample) at STP

Procedure: what to do in the virtual lab

1. Set 10 volume and 100 mL. Read M, N and the strength in g/L.
2. Change to 20 volume and 30 volume and see how every value grows in proportion.
3. Read the volume of oxygen from the sample and check it against V × volume of sample.
4. Use the graph to follow the oxygen collected during the decomposition.

Observations to make

• All the concentrations are proportional to the volume strength.
• A 100 mL sample of 20 volume H₂O₂ gives 2000 mL (2 L) of O₂ at STP.
• The molarity is always lower than the normality by a factor of 2.

What you can change in this experiment

• Volume strength of the solution (volumes)
• Volume of the sample taken (mL)

Viva questions on Volume strength of hydrogen peroxide

Questions an examiner may ask in the Class 11 chemistry practical. Run the experiment in the lab to find the answers yourself, then check them in the Learn tab.

1. What do you mean by 10 volume hydrogen peroxide?
2. How is the volume strength related to molarity?
3. What is the equivalent mass of H₂O₂?
4. How much oxygen is obtained from 50 mL of 20 volume H₂O₂?

Frequently asked questions

Syllabus: Class XI Chemistry, Chapter 1 — Some Basic Concepts of Chemistry (concentration of solutions); Chapter 9 — Hydrogen (strength of hydrogen peroxide)

What you do in the lab

Change the controls and watch the chemistry behave in real time in 3D. Live readouts and graphs show the numbers behind it, and the Learn tab has the theory, procedure, observations and viva questions. Works on a phone or a laptop, in English and Hindi.

Topics: volume strength of hydrogen peroxide · 20 volume H2O2 · molarity of H2O2 · normality · percentage w/v · decomposition of hydrogen peroxide · oxygen at STP · some basic concepts of chemistry

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