Question

How many moles of butane on complete combustion gives 18 g of water?

Answer 1

To determine the number of moles of butane that gives 18 g of water, we first need to set up the balanced chemical equation for the complete combustion of butane:

C4H10 + 13/2 O2 -> 4 CO2 + 5 H2O

From the equation, we can see that for every 13/2 moles of oxygen (O2), we obtain 5 moles of water (H2O). Therefore, the molar ratio between water and oxygen is 5:13/2, which simplifies to 10:13.

Now, we can calculate the number of moles of water based on the given mass and the molar mass of water:

Mass of water = 18 g
Molar mass of water (H2O) = 18 g/mol

Number of moles of water = Mass of water / Molar mass of water
= 18 g / 18 g/mol
= 1 mole

Since there is a 10:13 molar ratio between water and oxygen, the number of moles of oxygen required would be:

Number of moles of oxygen = Number of moles of water * (13/10)
= 1 mole * (13/10)
= 1.3 moles

Therefore, the complete combustion of butane that gives 18 g of water would require 1.3 moles of oxygen.