Nitrous acid disproportionates: HNO2 -> HNO3 + NO + H2O. Balance the equation and calculate the volume of NO at STP obtained from 9.4 g of HNO2. Atomic masses: H 1, N 14, O 16; molar volume at STP = 22.4 L/mol. Give the answer in litres to two decimal places.

JEE Advanced levelNumerical answerDifficulty 3 of 3rx090

Nitrous acid disproportionates: $HNO X_{2} HNO X_{3} + NO + H X_{2} O$ . Balance the equation and calculate the volume of NO at STP obtained from 9.4 g of $HNO X_{2}$ . Atomic masses: H 1, N 14, O 16; molar volume at STP = 22.4 L/mol. Give the answer in litres to two decimal places.

Numerical answer type, answer in L, tolerance 0.02.

Balanced:

3 HNO X_{2} HNO X_{3} + 2 NO + H X_{2} O

(1 N oxidised by 2 electrons, 2 N reduced by 1 each). Molar mass of

HNO X_{2}

= 47 g/mol, so n = 9.4/47 = 0.20 mol. n(NO) = 0.20 x 2/3 = 0.1333 mol and V = 0.1333 x 22.4 = 2.99 L.