Mg3N2 +6H2O- 3Mg(OH)2 + 2NH3-- How many grams of H2O are needed to produce 150g of Mg(OH)2?

Question

I thought I had this but.....the correct answer should be 93 grams
Where did I go wrong??

1) Change 150 g Mg(OH)2 into moles by dividing by molar mass from periodic table.
150 / (24 + 32 + 3) = moles

2) Ratio of chemicals is 6 H2O to 3 Mg(OH)2 - Multiply the #moles Mg(OH)2 by 3/6 which is the ratio of moles H2O to Mg(OH)2.

3) multiply by the mass of H2O from the periodic table. The mass of H2O is 18.

But.. the answer should be 93 grams
Thanks for your help!

Answer 1

I got it I take 18 and multiple by 5.172=93.1 g