[Boxxxed]

Ethane burns in air according to the following equation:  2C2H6 (g) + 7O2(g) → 4CO2 + 6H2O  What volume of O2 is required for complete reaction with 5.2 L of C2H6?  What volume of water vapour is produced?  Assume constant temperature and pressure.

How do I figure out the moles of C2H6 from the volume?

[JGK]

What is the volume of 1 mole of gas at STP?

If you start from there, you should be able to work it out.

[Boxxxed]

This would be easy if I had the mass. I'm not sure how to get volume from pressure or volume?

[sjb]

What does Avogadro's law state?

[Boxxxed]

v/n=k

How is n derived from any of these formulas?

[sjb]

v/n=k

How is n derived from any of these formulas?

Can you define your terms here? You could be right (as far as I know), but I'm not sure.

[Boxxxed]

volume over n(moles)=constant(k)

It is now cleared up that it is an approximation. At first it made no sense since different molecules are of different sizes. I still don't know how to derive moles from volume. Do I just use standard temperatures and pressure? How is a formula rearranged accordingly?

[opti384]

Do I just use standard temperatures and pressure?

Yes since the question does not give any specific temperature and pressure but states "assume constant temperature and pressure."

[sjb]

volume over n(moles)=constant(k)

So what that's saying is that for a given number of moles of gas, the volume is independent of the identity of the gas. You don't need to know the mass here.

[Borek]

volume over n(moles)=constant(k)

It is now cleared up that it is an approximation. At first it made no sense since different molecules are of different sizes. I still don't know how to derive moles from volume. Do I just use standard temperatures and pressure? How is a formula rearranged accordingly?

Actually it is a quite good approximation, as long as the gas behaves as an ideal one.

Question wants you to use the fact that if 1 moles of gas reacts with with 1 mole of other gas, their volume ratios are 1:1 as well.