How many grams of beryllium are needed to produce 36.0 g of hydrogen? Assume an excess of water.

Be(s) + 2H2O(L) --Be(OH)2(aq) + H2(g)

Can anyone explain this? I just don't really get it, I see there's a 1 to one relationship between Be and H2 but I'm not sure what to do

Question

How many grams of beryllium are needed to produce 36.0 g of hydrogen? Assume an excess of water.

Be(s) + 2H2O(L) -->Be(OH)2(aq) + H2(g)

Can anyone explain this? I just don't really get it, I see there's a 1 to one relationship between Be and H2 but I'm not sure what to do

anonymous · Answer

1 mole of Be = 9 grams. 1 mole of H = 1 gram. Therefore it takes 9 grams of Beryllium to form 1 gram of Hydrogen. So if there are 36 grams of Hydrogen it will take 36 x 9 grams of Beryllium. Understand? :D

cyber405 · Answer

Ivanthebear is right if  1mole Be=1mole H...

But if 1mole Be=1mole H2 then every mole of Be which is 9 grams takes to form 1mole 

of H2(which is 2 g)....so if there are 36 grams of H2 it will take (36/2) x 9 grams of Be.

OK?