If 3.40 mol calcium carbide (CaC2) reacts with an excess of water, how many moles of acetylene (C2H2) will be produced?
CaC2(s) + 2 H2O(l) Ca(OH)2(aq) + C2H2(g)

Please read this... Ask Me Help Desk - Announcements in Forum : Homework Help

We don't do your homework on here. This question is quite direct... you have your equation and your required info. Here, you're using 3.40 mol of CaC2, and you need to find the amount of moles of C2H2 produced. All is in the equation itself. If you didn't know, the equation tells you that for every one mole of CaC2 reacting with 2 moles of H2O, you get one mole of Ca(OH)2 and another mole of C2H2. By simple proportions, you can get your required answer. :)