methanol was made in lab. Equation- CO + 2H2 giving one mol of CH3OH.
A. how many grams of methanol would be produced in complete reaction. The answer is 40.3g. The reaction used 35.4g carbon monoxide and 10.2g hydrogen.
I'm not sure what to do but I thought that I would find the number of moles of CO and H by dividing mass with Mr and I got 0.79 for CO and 0.39 for H and from the equation I know a mol of CO and 2 of H produce 1 of CH3Oh. But from here I don't know how to get to 40.3g.

CO + 2H2 = CH3OH

35.4 g of CO is about 1.26 moles of CO (divide 35.4 by the molecular weight of CO).
10.2 g of H2 is about 5.1 moles of H2.

since you need 2 moles of H2 for every mole of CO, 5.1 moles of H2 would require 2.55 moles of CO.

40.3 grams of CH3OH is about 1.26 moles of CH3OH.

The number of moles of CO is equal to the number of moles of CH3OH so apparently H2 is present in excess.

I'm not sure where you got the 0.79 for CO or the 0.39 for the H (remember it's H2, not H).

Hope this helps.
Good luck,