Na2S + Zn(NO3)2 = ZnS + 2NaNO3 Given: 625g Zinc Sulfide. Need:grams of Zinc Nitrate to make ZnS in 85% yield?

Question

A student needs 625g of Zinc Sulfide. He can synthesize is using the reaction: Na2S + Zn(NO3)2 = ZnS + 2NaNO3

How many grams of zinc nitrate is needed if he can make the zinc sulfide in 85% yield. Assume he is using excess of sodium sulfide.

Answer 1

625g ZnS x 1mol ZnS/97g ZnS x 1mol Zn(NO3)2/1mol ZnS x 189g Zn(NO3)2/1mol Zn(NO3)2 x 100/85 = 1433g Zn(NO3)2

Zn=65 S=32 NO3=62