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

Because a model would make the investigation easier to understand

Adozen is 1221/12 = 1.751.75 x 12 = 21therefore, 1.75 is the answer.