How many moles of pcl5 can be produced from 23.0 g of p4 (and excess cl2) ?

The balanced equation for the above reaction is as follows

P4 + 10Cl2 - > 4PCl5

P4 is the limiting reactant. Stoichiometry of P4 to PCl5 is 1:4

The mass of P4 reacted = 23.0 g

Number of P4 moles = 23.0 g / 124 g/mol = 0.185 mol

According to the stoichiometry the number of PCl5 moles produced are 4 times the amount of P4 moles reacted

Therefore PCl5 moles = 0.185 x 4 = 0.74 mol