A limestone sample is 80% CaCO3 by mass (100 g/mol). 40.0 g of it is treated with excess dilute HCl and the CO2 is collected with an 85% yield. Find the volume of CO2 at STP in litres (molar volume 22.4 L/mol), to two decimals.

JEE Main levelNumerical answerDifficulty 2 of 3mc066

A limestone sample is $80%$ $CaCO X_{3}$ by mass ( $100 g/mol$ ). $40.0 g$ of it is treated with excess dilute $HCl$ and the $CO X_{2}$ is collected with an $85%$ yield. Find the volume of $CO X_{2}$ at STP in litres (molar volume $22.4 L/mol$ ), to two decimals.

Numerical answer type, answer in L, tolerance 0.02.

Pure

CaCO X_{3}

= 40.0 x 0.80 = 32 g = 0.32 mol, giving 0.32 mol

CO X_{2}

theoretically. At 85% yield: 0.32 x 0.85 = 0.272 mol. Volume = 0.272 x 22.4 = 6.0928 L, about 6.09 L.