Question

Carbon dioxide can be made in the lab by the reaction of hydrochloric acid with calcium carbonate. How many milliliters of dry CO2 at 20.0 °C and 745 torr can be prepared from a mixture of 30.6 g of CaCO3 and 279 mL of 0.250 M HCl?

Answer 1

This is a limiting reagent (LR) problem.

CaCO3 + 2HCl ==> H2O + CO2 + CaCl2
mols CaCO3 = grams/molar mass
mols CO2 = mols CaCO3 (from the coefficients in the balanced equation).

mols HCl = M x L = ?
mols CO2 = 1/2 that (do the coefficient thing again.)
The values for mols CO2 produced probably will not agree which means one of them is not right. In LR problems the smaller value is ALWAYS the correct value and the reagent producing that value is the limiting reagent.
Using the smaller value for n, use PV = nRT and solve for V in liters and convert to mL.
NOTE!!!!. I highly suspect that the person making up this problem wants you to correct for the vapor pressure of H2O; however, the way the problem is stated that correction is not necessary. The way I have worked the problem is for dry CO2 and says nothing about how the CO2 is collected. IF it is collected over water AND has these same parameters, then a correction is necessary.
Use PV = nRT and the conditions lis