# Suppose 9.5 g of gaseous C2H2 reacts with excess O2 according to the reaction below. What is the mass of CO2 produced? C2H2(g) + O2(g) → CO2(g) + H2O(ℓ)

Jun 8, 2014

Firstly we need to correct the equation - it isn't balanced as you wrote it. For the complete combustion of ethyne|
${C}_{2} {H}_{2} + 2 \frac{1}{2} {O}_{2} \to 2 C {O}_{2} + {H}_{2} O$

So, the stoichiometry tells us that 1 mole of ethyne makes 2 moles of carbon dioxide.

Moles of ethyne = mass of ethyne / ${M}_{r}$ of ethyne = 9.5/26 = 0.365 moles

Moles of $C {O}_{2}$ = moles of ethyne x 2 = 0.731

Mass of $C {O}_{2}$ = moles of $C {O}_{2}$ x ${M}_{r}$ of $C {O}_{2}$ = 0.731 x 44 = 32.15g