Question

Calculate the mass of nitrogen in 2240 cm³ of nitrogen dioxide at S.T.P.

Answer 1

Given:

Volume of nitrogen dioxide (NO₂) = 2240 cm³

At STP, 1 mole of gas = 22,400 cm³

Molar mass of NO₂ = 14 + 2(16) = 46 g/mol

1. Number of moles of NO₂:

Moles = `2240/22400` ​= 0.1 mol

Each molecule of NO₂ contains 1 nitrogen atom.

Therefore, 0.1 mol of NO₂ contains 0.1 mol of nitrogen.

Mass of nitrogen = 0.1 × 14 = 1.4 g​