Assuming that the reactions are complete, calculate the percentage by mass of magnesium carbonate in the mixtu?

A 6.54 g sample of a mixture of magnesium carbonate and calcium carbonate is treated with excess hydrochloric acid. The resulting reaction produces 1.73 L of carbon dioxide gas at 29

Celcius and 743 torr pressure.Assuming that the reactions are complete, calculate the percentage by mass of magnesium carbonate in the mixtu?
p = 743/760=0.978 atm

T = 29 + 273 = 302 K

moles CO2 = 0.978 x 1.73 / 0.08206 x 302 =0.0682



x = mass MgCO3 molar mass =84.4 g/mol

y = mass CaCO3 molar mass = 100 g/mol



x + y = 6.54

x/ 84.4 + y /100= 0.0682



100 x + 84.4 y =575.6



100 x + 84.4 ( 6.54 -x) = 575.6



100 x + 552 - 84.4 x = 575.6



15.6 x = 23.6

x = 1.51 g



% = 1.51 x 100/ 6.54=23.1