V 2 O 5 + Cl 2  VOCl 3 + O 2

How many moles of V 2 O 5 are required to produce 7.0 moles of VOCl 3?

Answer: 3.5 moles V2O5

Explanation: First balance the chemical equation to find the stoichiometric factor between VOCl3 and V2O5

2 V2O5 + 6 Cl2 = > 4 VOCl3 + 7 O2

So the mole to mole ratio is 2 moles V2O5 to 4 moles of VOCl3

Solution

7 moles VOCl3 x 2 moles V2O5 / 4 moles VOCl3 = 3.5 moles V2O5