[Taz]

Hey, I'm totally lost with these three problems. Can someone please help me with them, and include the actual formula needed for me to do them myself?

1: What mass of carbon dioxide is produced from the complete combustion of 2.80x10^-3g of methane?

2: What mass of water is produced from the complete combustion of 2.80x10^-3g of methane?

3: What mass of oxygen is needed for the complete combustion of 2.80x10^-3g of methane?

Any help would be greatly appreciated. these are from Pearson and the "hints" only display the same question a different way, rather than helping me figure out how to do this.

[sjb]

What is the balanced equation for the reaction?

[Andy_Ruan]

You will first need to get a balanced equation for the combustion reaction.
e.g CH4 + 2 O2 -> CO2 + 2 H2O     (you will need to balance the coefficients based on the type of hydrocarbon)

Afterwards, you will need to calculate the # moles of hydrocarbon using n = m/M
And once you find the # moles of hydrocarbon, you can easily calculate the theoretical # moles
of CO2 or H2O produced and convert that back to mass using the same equation 3 lines above!

hope this helps

[DeanC]

It's a useful tip to get into the habit of always starting questions by writing out a balanced equation. Once you can calculate the no. of moles of one of the reagents, the stoichiometry will allow you to calculate any of the other species with ease.

It may not apply to this question persay but keep in mind the limiting reagent when calculating masses or moles using a stoichiometric balanced equation also.

Best of luck!