Answer:
mass of Clâ‚‚ = 1.46 g
Explanation:
given data
mass of phosphorus trichloride  = 3.66 G
mas of chlorine gas = ?
efficiency = 83.7 %
balanced chemical equation
   2P + 3Cl₂ → 2PCl₃
The mole ration of chlorine and phosphorus trichloride = 3 : 2
First we will find out number of moles of Cl₂ and PCl₃
As we know that:
    number of moles = mass / molar mass
    number of moles of PCl₃  =  3.66 g / 137.33 g.mol-
    number of moles of PCl₃  = 0.027 mol
As the mole ratio of PCl₃ and Cl₂ = 2 : 3
   so number of moles of Cl₂  = (0.027 ×3) / 2
   number of moles of Cl₂  = 0.041
Now we find the mass of Clâ‚‚
   mass of Cl₂ = moles × molar mass
  mass of Cl₂ = 0.041 mol × 35.5 g/mol
  mass of Cl₂ = 1.46 g