Question

{1} 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 {2} 10g of phosphine reacts with 15g of chlorine gas to produced 5.5g of phosphorus pentachloride calculate the percentage yield {3} calculate the wave length in meter/second associated with an 80g of mass moving at 3km/hr

Answer 1

(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

= 71 × 0.2876

= 20.419 g

(2) from above reaction,

it is clear that, 2 moles of phosphine reacts with 8 moles of chlorine gas.

so, 68g of phosphine reacts with 284g of chlorine gas.

or, 10g of phosphine reacts with 284/68 × 10 = 41.76g,but given only 15g of Cl2.

so, Cl2 is limiting reagent.

from reaction, 8 moles of Cl2 forms 2 moles of PCl5

so, 284g Cl2 forms 417g of PCl5

or, 15g of Cl2 forms 417/284 × 15 g = 22g

given, experimental yield = 5.5g

so, percentage yield = 5.5/22 × 100 = 25%

(3) using De-broglie wavelength equation,

wavelength = h/mv

here, h = 6.6 × 10^-34 js, m = 80g = 0.08kg and v = 3km/h = 3 × 5/18 = 5/6 m/s

so, wavelength = 6.6 × 10^-34/(0.08 × 5/6) = 99 × 10^-34 = 9.9 × 10^-33 m

Answer 2

1) 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

2)  given  10g of phosphine reacts with 15g of chlorine gas to produced 5.5g of phosphorus pentachloride

But according to equation  ,

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.

we can see clearly that PH3 is excess reagent and Cl2 is limiting reactant.

so

568 g of chlorine gives 417g of PCl5  

15g of cl2 ------------?

= 15x417/568

=6255/568

=11.0g of PCl5

for experiment  yield is 5.5g

∴Percentage yield = (5.5 /11 )x100

=50%

3) wavelength = h/mv [De-Broglie wavelength equation]

where

h= 6.6 × 10⁻³⁴ js,

m = 80g = 0.08kg

and v = 3km/h = 3 × 5/18 = 5/6 m/s

wavelength=6.6 ×10⁻³⁴ x6/0.08 x5

=39.6x10⁻³⁴ x6.6  / 0.4

=99x 10⁻³⁴

=9.9x 10⁻³³ m