Question

2NaBr + CaF2 → 2NaF + CaBr2, 4 moles NaBr react with 3 moles of CaF2. Which substance is the limiting reagent?

NaBr

CaF2

NaF

CaBr2

Answer 1

look at the mole ratio based on the number of moles of NaBr
2:1
4:x
4*1/2= moles of CaF2
Now look again at the mole ration based on the number of moles of CaF2
2:1
x:3
3*2/1=6 moles of NaBr
NaBr moles reacting is less than calculated therefore NaBr is the limiting reagent.