Question

What is the amount (in moles) of calcium carbonate in a 7.25 g sample of limestone if the gravimetric analysis found that the sample contained 65.2% calcium carbonate?

Answer 1

To find the amount of calcium carbonate in moles, we first need to determine the mass of calcium carbonate in the sample and then convert it to moles using the molar mass of calcium carbonate.1. Calculate the mass of calcium carbonate in the sample:Mass of calcium carbonate =  Percentage of calcium carbonate / 100   Mass of limestone sampleMass of calcium carbonate =  65.2 / 100   7.25 gMass of calcium carbonate = 0.652  7.25 gMass of calcium carbonate  4.727 g2. Calculate the molar mass of calcium carbonate  CaCO3 :Molar mass of CaCO3 =  1  Molar mass of Ca  +  1  Molar mass of C  +  3  Molar mass of O Molar mass of CaCO3 =  1  40.08 g/mol  +  1  12.01 g/mol  +  3  16.00 g/mol Molar mass of CaCO3 = 40.08 g/mol + 12.01 g/mol + 48.00 g/molMolar mass of CaCO3  100.09 g/mol3. Convert the mass of calcium carbonate to moles:Amount of calcium carbonate in moles = Mass of calcium carbonate / Molar mass of CaCO3Amount of calcium carbonate in moles = 4.727 g / 100.09 g/molAmount of calcium carbonate in moles  0.0472 molTherefore, there are approximately 0.0472 moles of calcium carbonate in the 7.25 g sample of limestone.