Question

Consider the reaction below
Al2S3(s) + H2O(l) → Al(OH)3(s) + H2S(g)
If 15.0g of aluminum sulfide and 10.0g of water are allowed to react as above, and assuming a complete reaction
a. by calculation, find out which is the limiting reagent.
b. calculate the maximum mass of H2S which can be formed from these reagents.
c. calculate the mass of excess reagent remaining after the reaction is complete.
PLEASE HELP

Answer 1

can anyone tell me how to find the Limitant and Excess reactant? no, i dont want the math answer or the equations. i know i have to calculate Al2S3 and H2O, but i just want to know what element from the product i have to use because im lost. i repeat i know the math so a simple explanation or "walk thru" the problem would be great. thanks

Answer 2

You need to figure out the relative NUMBER of each reactant to determine which is limiting. You're given masses, so convert those to moles (a number) by dividing each mass by the corresponding molar mass. Once you have the number of moles of each reactant, divide that by the corresponding stoichiometric coefficient in the chemical reaction to determine the relative amounts of each reactant. The lower of the numbers is the limiting reactant, and that is the one you should then use to set up stoichiometric ratios to determine the yield of products of interest (in moles), as well as the amount (in moles) of the excess reactant that is consumed by the reaction. You can do some simple calculations then to find the masses or the amount of excess reactant that remains.