Calculate how many moles of the second reactant would be required to react completely with 5.00 mol of the first reactant.
C2H6(g) + O2(g)--->CO2(g) + H2) (g)
I have about a dozen of these for homework. Been working on them for hours
Can anyone help?

It is very easy. I'll just give you an example and you will try by yourself.

C (s) + O2 (g) -> CO2 (g)

There are no numbers in front of the reactants. Therefore one mole of C is reacting with one mole of O2.

In another situation;

3Fe (s) + O2 (g) -> Fe3O2 (s)

Whereby three moles of Fe react with one mole of O2. Understand?