Question

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)

Answer 1

Firstly we need to correct the equation - it isn't balanced as you wrote it. For the complete combustion of ethyne|
`C_2H_2 + 2 1/2 O_2 -> 2CO_2 + H_2O`

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 `CO _2` = moles of ethyne x 2 = 0.731

Mass of `CO_2` = moles of `CO_2` x `M_r` of `CO_2` = 0.731 x 44 = 32.15g