First what you want to do is balance the chemical equation. Then you find the molar mass of both products. After this is done what you want to do is pick one compound on the reactant side (doesnt matter which one) then you take the mass given to you and divide it by the molar mass you found. Then take that number and multiply it by the mole to mole ratio which is what you want divided by what you don't want. And your mole to mole ratio comes from the coefficient in front of the equation which you balanced. Then after this is done you want to multiple the number you got after doing the mole to mole ratio by the molar mass of the other compound on the reactant side of the equation. After this you get a number. Now if the number you received is more than what they give you then it is the limiting reactant. If it is less it is the excess reactant. =)
