Question

A mixture of carbon and sulfur has a mass of 9.0 g. Complete combustion with excess O2 gives 29.7 g of a mixture of CO2 and SO2.Find the mass of sulfur in the original mixture.

Answer 1

C + O2 ==> CO2
S + O2 ==> SO2

Let X = g C
and Y = g S
-----------
eqn 1 is X + Y = 9.0

g CO2 + g SO2 = 29.7
Convert this word equation into eqn 2 in terms of X and Y.(MM is molar mass and AM is atomic mass.)
X(MM CO2/AM C) + Y(MM SO2/AM S) = 29.7

Solve eqn 1 and eqn 2 for Y = g S in the original mixture.