Question

4 gram hydrogen react with 9 into 10 to the power 23 chlorine molecule and form HCL gas if the total pressure of the system after the reaction is 700 millimetre what is the partial pressure of HCL

Answer 1

• Partial pressure of HCl is 600 mm of Hg.

Given

• Weight of Hydrogen = 4 gram

• Moles of Hydrogen = 4/2 = 2 moles

• Molecules of chlorine = 9 × 10²³

• Moles of Chlorine = 9 × 10²³/ 6.023 × 10²³ = 1.498 moles

• Total pressure = 700 mm of Hg

Reaction is -

                          H₂       +     Cl₂          →       2 HCl

Initially            2 moles     1.498 moles         0 moles

Since moles of chlorine is less than hydrogen, so chlorine is the limiting reagent here and Hydrogen will be the excess reagent.

1 mole chlorine reacts with 1 mole of hydrogen

1.498 moles of chlorine reacts with 1.498 moles of hydrogen.

So, moles of hydrogen left is = 2 -1.498 = 0.502

1 mole of chlorine forms 2 moles of HCl

So 1.498 moles of chlorine will forms 2 × 1.498 = 2.996 moles of HCl

Total moles after the reaction is = 2.996 + 0.502 = 3.498

Partial pressure of HCl = Total pressure × Mole fraction of HCl

                                      =  700 × 2.996/3.498

                                      =  599.5 ≈ 600 mm of Hg

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