Finding the limiting reagent of a chemical equation?

When 20.00g of Cl2 and 20.00g of CH4 react, which is the limiting reagent? My chemical equation is 4Cl2 + CH4 ----> CCl4 + 4HCl. I think I have to convert the moles to grams now but i'm not sure, how do I know which of the two is the limiting reagent once i've solved and once i've found the limiting reagent is the other answer the excess reagent or do I have to do a whole other problem to find that?