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For the reaction PC15 (8) PC13 (g) + Cl2 (g) K = 0.0454 at 261 °C. If a vessel is filled with these gases such that the initial concentrations are [PC15) = 0.20 M, [PC13] = 0.20 M, and (Cl21 = 2.5 M, in which direction will a reaction occur and why? A) toward products because Qc = 0.56 B) toward reactants because Qc = 2.5 C) toward products because Qc = 2.8 D) toward reactants because Qc = 0.0454 E) it is at equilibrium because Qc = 1

User Spacehunt
by
8.1k points

2 Answers

3 votes

Answer: The reaction proceed toward reactants because
Q_c is 2.5

Step-by-step explanation:


K_c is the constant of a certain reaction at equilibrium while
Q_c is the quotient of activities of products and reactants at any stage other than equilibrium of a reaction.

For the given chemical reaction:


PCl_5(g)\rightleftharpoons PCl_3(g)+Cl_2(g)

The expression of
Q_c for above equation follows:


Q_c=([PCl_3][Cl_2])/([PCl_5])

We are given:


[PCl_3]=0.20M


[Cl_2]=2.5M


[PCl_5]=0.20M

Putting values in above equation, we get:


Q_c=(0.20* 2.5)/(0.20)=2.5

We are given:


K_c=0.0454

There are 3 conditions:

  • When
    K_(c)>Q_c; the reaction is product favored.
  • When
    K_(c)<Q_c; the reaction is reactant favored.
  • When
    K_(c)=Q_c; the reaction is in equilibrium.

As,
Q_c>K_c, the reaction will be favoring reactant side.

Hence, the reaction proceed toward reactants because
Q_c is 2.5

User Eleanor Holley
by
7.8k points
2 votes

Answer:

The correct answer is B.

The
K_(eq) is samller than
Q of the reaction . So,the reaction will shift towards the left i.e. towards the reactant side.

Step-by-step explanation:

Equilibrium constant is defined as the ratio of concentration of products to the concentration of reactants each raised to the power their stoichiometric ratios. It is expressed as
K_(eq)

K is the constant of a certain reaction when it is in equilibrium, while Q is the quotient of activities of products and reactants at any stage other than equilibrium of a reaction.

For the given chemical reaction:


PCl_5(g)\rightleftharpoons PCl_3(g)+Cl_2(g)

The expression for
Q is written as:


Q=([PCl_3][Cl_2])/([[PCl_5]^1)


Q=(0.20 M* 2.5 M)/(0.20 M)


Q=2.5

Given :
K_(eq) = 0.0454

Thus as
K_(eq)<Q, the reaction will shift towards the left i.e. towards the reactant side.

User WebNeat
by
7.6k points
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