A 10.00 g sample of pure NaHCO3 is heated until the mass is constant, according to 2NaHCO3 -> Na2CO3 + H2O + CO2. Using atomic masses H = 1, C = 12, O = 16, Na = 23, calculate the mass of the solid residue in grams, correct to two decimal places.

JEE Main levelNumerical answerDifficulty 2 of 3sb028

A $10.00 g$ sample of pure $NaHCO X_{3}$ is heated until the mass is constant, according to $2 NaHCO X_{3} Na X_{2} CO X_{3} + H X_{2} O + CO X_{2}$ . Using atomic masses H = 1, C = 12, O = 16, Na = 23, calculate the mass of the solid residue in grams, correct to two decimal places.

Numerical answer type, answer in g, tolerance 0.01.

Molar mass of

NaHCO X_{3}

84 g mo l^{- 1}

and of

Na X_{2} CO X_{3}

106 g mo l^{- 1}

. Moles of

NaHCO X_{3}

10.00/84 = 0.1190

. Two moles give one mole of

Na X_{2} CO X_{3}

, so the moles of residue are

0.0595

. Mass =

0.0595 \times 106 = 6.31 g