Question

What mass of chlorine gas would be required to produce 0.015kg of phosphorus pentachloride?

Answer 1

2 PH3 + 8 CL2 = 2 PCL5 + 6 HCL

M(Cl2) = 71 g/mol

M(PCL5) = 208.24 g/mol

M(PH3) = 40.0 g/mol

From the equation :

568 g (CL2) = 416.48 g (PCL5)

x g (Cl2) = 15 g (PCL5)

x = 568*15/416.48 = 20.46 g (CL2)

From the equation we can see, that PH3 is an excess. So the calculations are carried out on chlorine.

Answer 2

Phosphorus pentachloride is produced by the reaction between phosphine and chlorine gas.

The required chemical equation is :

2PH₃ +8Cl₂ ---->2PCl5 + 6HCl

its clear that 2 moles of Phosphine reacts with 8 moles of chlorine to give 2 moles of phosphorous penta chloride and 6 moles of hydrochloric acid.

molecular mass of chlorine = Cl2= [ 2x 35.5] =71 u

Molecular mass of PCl5 = [ 31+ 5x35.5]= [ 31+177.5]=208.5 u

568 g of chlorine gives 417g of PCl5  

? ------------? 0.015KG (15g)

= 568x 15/417

=8520/417

=20.43 g

∴ 20.43 g of chlorine gas  is required to produce 0.015kg of phosphorus pentachloride