What mass of propane (C3H8) is needed to produce 346 g carbon dioxide in the following reaction?

The only possible reaction for conversion of a hydrocarbon to carbon dioxide is combustion reaction

Combustion is burning of a substance in presence of oxygen

In case of sufficient supply of oxygen the hydrocarbon converts to carbon dioxide and water.

The general reaction for combustion of any hydrocarbon will be

CxHy + (x + y/4) O2 (g) - --> xCO2 (g) + y/2H2O

In the given problem we have propane and the balanced combustion equation will be

C3H8 (g) + 5O2 (g) - --> 3CO2 (g) + 4H2O

As per equation, one mole of propane (molar mass 44g/mol) is required for production of three moles of carbon dioxide (molar mass 44 g/mol)

3 moles of carbon dioxide will weigh 3 X 44 = 132 g

So

132g of carbon dioxide need 44g of propane

1 g of carbon dixoide needs 44 / 132 g of propane

346g of carbon dioxide need = 44 x 346 / 132 g of propane = 115.33 g of propane