The molarity of 20 volume H₂O₂ is nearly

Solution:

The volume strength of H₂O₂ is defined as the volume of oxygen gas (at STP) liberated from 1 volume of the H₂O₂ solution upon decomposition. The decomposition reaction is:

2H₂O₂(aq) → 2H₂O(l) + O₂(g)

From the stoichiometry, 2 moles of H₂O₂ produce 1 mole of O₂.

At STP, 1 mole of O₂ occupies 22.4 L.

A "20 volume" H₂O₂ solution means that 1 L of the solution produces 20 L of O₂ at STP.

Moles of O₂ produced from 1 L solution = Volume of O₂ / Molar volume of O₂ at STP = 20 L / 22.4 L/mol ≈ 0.893 mol.

From the reaction, 1 mole of O₂ is produced from 2 moles of H₂O₂.

So, moles of H₂O₂ in 1 L solution = 2 × Moles of O₂ = 2 × 0.893 mol ≈ 1.786 mol.

Molarity = Moles of H₂O₂ / Volume of solution in L = 1.786 mol / 1 L = 1.786 M.

This value is approximately 1.8 M.