The reaction between phosphorus (P4 ) and hydrogen (H2 ) can result in the formation of phosphine (PH3 ) as shown: mathrmP4( mathrm~s)+6 mathrmH2( mathrm~g) leftharpoons 4 mathrmPH3( mathrm~g) The graph shows the change in concentration of hydrogen for this reaction in which the system was disturbed after four hours. Which of the following could explain the change in hydrogen concentration at time = 4 hours?

Question

The reaction between phosphorus (P4 ) and hydrogen (H2 ) can result in the formation of phosphine (PH3 ) as shown: mathrmP4( mathrm~s)+6 mathrmH2( mathrm~g) leftharpoons 4 mathrmPH3( mathrm~g) The graph shows the change in concentration of hydrogen for this reaction in which the system was disturbed after four hours. <img class="img-fluid question-image" alt="Question" src="https://cdn.tardigrade.in/q/nta/c-2sblsdbjf0yw.png" /> Which of the following could explain the change in hydrogen concentration at time = 4 hours? (A) The volume on the reaction vessel was decreased (B) A catalyst was added (C) The pressure on the reaction mixture was decreased (D) More phosphorus was added

Tardigrade Admin · Accepted Answer

Volume of the vessel was decreased, which led to sudden increase in [H₂ ]. The reaction then moves in direction to achieve a state of new equilibrium.

A catalyst does not affect the equilibrium concentration of reactants and products.

Increase in pressure would decrease concentration as reaction favoured forward.

P₄(s) will have no effect on k_P and concentration of H₂(g)

( because active mass of solid is taken to be unit )