Sodium borohydride (NaBH4) is used industrially in many organic syntheses. One way to prepare it is by reacting sodium hydride with gaseous diborane (B2H6). Assuming an 88.5% yield, how many grams of NaBH4 can be prepared by reacting 7.98g of sodium hydride and 8.16 g of diborane?

Question

btaylor · Answer

Balanced equation:
   2 HNa + B2H6 --> 2 NaBH4
You have .333 mol HNa and .318 mol of B2H6. Since the HNa is used up twice as fast, it will be consumed first. So, when all .333 mol HNa are gone, it will form .333 mol of NaBH4, which is 12.6 grams. But you multiply that by 88.5%, since that is your % yield. you get 11.151 g NaBH4.
get it?