Question

phosphorus pentachloride is produced by the reaction between phosphine and chlorine gas. what mass of chlorine gas would be required to produced 0.015kg of phosphorus pentachloride

Answer 1

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

reaction is ....

$2PH_3+8Cl_2\rightarrow2PCl_5+6 HCl$,

it is clear that, 8 moles of chlorine produced 2 moles of phosphorus pentachloride.

so, 1 mole of chlorine gas will produce 2/8 = 0.25 mole of phosphorus pentachloride.

or, 1 mole of phosphorus pentachloride is produced by 4 mole of chlorine gas.

given, mass of phosphorus pentachloride is produced = 0.015kg = 15g

molecular mass of PCl5 = 31 + 5 × 35.5 = 31 + 177.5 = 208.5 g/mol

so, mole of phosphorus pentachloride = 15/208.5 = 0.0719

now mole of chlorine gas is required to produce 0.0719 mole of phosphorus pentachloride = 4 × 0.0719 = 0.2876

so, mass of chlorine gas = molecular weight × number of mole

= 70 × 0.2876

= 20.132 g

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