Potash is composed mainly of potassium carbonate, K2CO3. If 1.000g of potash reacts with sulfuric acid to produce 145 mL of carbon dioxide gas at STP, what is the percentage of potassium carbonate in the marble sample?

Question

K2CO3 + H2SO4 ==> K2SO4 + H2O + CO2

Answer 1

145 mL x (1L/1000 mL) x (1 mole/22.4L) = ? moles CO2.
Convert moles CO2 to moles K2CO3 by
moles K2CO3 = moles CO2 x (1 mole K2CO3/1 mole CO2) = ?
grams CO2 = moles CO2 x molar mass CO2
%K2CO3 = (grams CO2/1.00 g sample) x 100 = ?