Here is the question:
"Limestone is an ore of calcium that contains a high proportion of calcium carbonate (CaCO3).
Calcium carbonate reacts with hydrochloric acid (HCl) according to the equation:
CaCO3 + 2HCl -> CaCl2 + CO2 +H2O
A 1.75g sample of limestone is added to a solution of excess hydrochloric acid at a pressure of 101 kPa. 280cm3 of carbon dioxide gas (CO2) is formed at a temperature of 22.0 degrees C. It was assumed that all of the CO2 gas produced was formed during the reaction between CaCO3 and HCl.
Calculate the percentage of CaCO3 in the limestone sample. (The gas constant, R = 8.31 J K^-1 mol^-1)"
Very wordy question, idk where to begin. I think by calculating the number of moles in the CO2 gas? What would I do next?