If 4.70 mol of calcium carbide (CaC2) reacts with an excess of water, how many moles of acetylene (C2H2), a gas used in welding, will be produced?

Question

CaC2(s) + 2 H2O(l) Ca(OH)2(aq) + C2H2(g)
mol

Answer 1

You need to find the arrow key and use it.
CaC2(s) + 2H2O(l)=> Ca(OH)2(aq) + C2H2(g)

Use the coefficients to convert anything to any other reactant or product.
4.7 mol CaC2 x (1 mol C2H2/1 mol CaC2) = 4.7 x 1/1 = 4.7 mol C2H2.
Note that the units you don't want cancel (that's mol CaC2) and leaves the unit you want to convert to (C2H2).
4.7 mols CaC2 will required 2*4.7 mols H2O and will produce 1 mol Ca(OH)2.