Question

Calculate the mass of butane needed to produce 50.0 g of carbon dioxide.

Answer 1

C4H10 + O2 --> CO2 + H2O

The mass must be balanced:

2C4H10 + 13O2 --> 8CO2 + 10H2O

The molar mass of butane is 12 × 4 + 10 = 58

The molar mass of carbon dioxide is 16 × 2 + 12 = 44

First, we calculate the moles of carbon dioxide produced

`n_(CO2) = (50,0 g)/(44 g/mol) = 1,14 mol`

If 2 moles of butane are needed for produce 8 moles of CO2 then x moles of butane are needed to produce 1,14 moles of CO2, therefore

`(2)/(8) = (x)/(1,14) \\ \\ x = (1,14)/(4) = 0,285 mol`

Then the moles can be multiplied by the molar mass of butane in order to get the total mass of butane burned.

`m_(C4H10) = 0,285 mol × 58 g/mol = 1,65 g`