Question

A) The equilibrium between carbon dioxide gas and carbonic acid is very important in biology and environmental science.

CO2 (aq) + H2O (l) H2CO3 (aq)
Which one of the following is the correct equilibrium constant expression (Kc) for this reaction?
a) K =[H2CO3]/ [CO2]
b) K=[CO2]/ [H2CO3]
c) K=[H2CO3]/ [CO2][H2O]
d) K=[CO2][H2O]/ [H2CO3]
e) K=1/[H2CO3]
B) For the reaction PCl3(g) + Cl2(g) <-->PCl5(g) at a particular temperature, Kc = 24.3. Suppose a system at that temperature is prepared with [PCl3] = 0.10 M, [Cl2] = 0.15 M, and [PCl5] = 0.60 M. Which of the following is true based on the above?
a) Qc > Kc, the reaction proceeds from right to left to reach equilibrium
b) Qc < Kc, the reaction proceeds from right to left to reach equilibrium
c) Qc > Kc, the reaction proceeds from left to right to reach equilibrium
d) Qc < Kc, the reaction proceeds from left to right to reach equilibrium
e) Qc = Kc, the reaction is currently at equilibrium

Answer 1

Step-by-step explanation:

CO₂ (aq) + H₂O (l) ⇄ H₂CO₃ (aq)

Equilibrium constant

Kc = [H₂CO₃] / [CO₂] [H₂O]

B )

PCl₃(g) + Cl₂(g) <--> PCl₅(g)

Kc = 24.3 .

[PCl₃] = .10M ,

[Cl₂] = 0.15 M

[PCl₅] = 0.60 M.

Qc = [PCl₅] / [PCl₃] [Cl₂]

= .60 / .10 x .15

= 40

Qc > Kc

Hence the reaction will proceed from left to right to reach equilibrium . It is so because the product concentration is more .

Option C is the right choice .