Question

For the reaction `CH_4 + 2O_2 -> CO_2 + H_2O`, how many moles of carbon dioxide are produced from the combustion of 100g of methane?

Answer 1

The moles of carbon dioxide produced from 100 g methane is 6 moles.

Explanation:

Balanced Equation

`"CH"_4 + "2O"_2"` `rarr` `"CO"_2 + "2H"_2"O"`

First, the given mass of methane must be converted to moles. For this you need the molar mass. The molar mass of `"CH"_4` is `"16.043 g/mol"`.
https://www.ncbi.nlm.nih.gov/pccompound/?term=methane

Multiply the given mass by the inverse of its molar mass.

`100color(red)cancel(color(black)("g CH"_4))xx(1"mol CH"_4)/(16.043color(red)cancel(color(black)("g CH"_4)))="6 mol CH"_4` (rounded to one sig fig based on 100 g)

Now multiply the moles methane by the mole ratio between methane and carbon dioxide so that methane is canceled.

`6color(red)cancel(color(black)("mol CH"_4))xx(1"mol CO"_2)/(1color(red)cancel(color(black)("mol CH"_4)))="6 mol CO"_2` (rounded to one sig fig based on 100 g)