need chemistry help

Question

How many moles of oxygen gas are required to completely combust 19.2g of methane gas (CH4)

Answer 1

Hello, Molly,

A balanced equation is needed.

Try CH₄ + 2O₂ = CO₂ + 2H₂O

If this is correct, we need 2 moles of oxygen to combust 1 mole of methane. Make this a conversion factor:

(2 moles O₂)/(1 mole CH₄)

Let's find the number of moles of methane:

Molar mass CH₄ = 16.04 g/mole

Moles CH₄ = (19.2 g CH₄)/(16.04 g/mole) = 1.20 moles CH₄

Use the conversion factor. Since we need twice as many moles of O₂ than CH₄, we need:

(1.20 moles CH₄)*(2 moles O₂)/(1 mole CH₄) = 2.40 moles O₂

Bob