Question

For the reaction CO2(g) + H2O(ℓ) + CaCl2(aq) ←→ CaCO3(s) + HCl(aq) K = 4.8 the concentrations of CO2, H2O, CaCl2 and HCl are 0.377 M, 55.4 M, 0.652 M and 30.2 M, respectively. What will happen in order for the system to reach equilibrium? 1. The reaction will shift to the right. 2. Nothing will occur. 3. The reaction will shift to the left. 4. Not enough information is given.

Answer 1

Answer:

3. The reaction will shift to the left.

Explanation:

Hello,

In this case, since we have a heterogeneous equilibrium, and the given equilibrium constant is given in terms of concentration, the law of mass action takes the following form:

$CO_2(g) + H_2O(l) + CaCl2(aq) \rightleftharpoons CaCO_3(s) + 2HCl(aq)$

$K=\frac{[HCl]^2}{[CaCl_2]}$

Clearly, just the hydrochloric acid and the calcium chloride participate in the equilibrium as they are the only aqueous species. Nonetheless, the given concentrations are not defining the equilibrium, therefore, one computes the reaction quotient in order to predict what would the system do to reach equilibrium as shown below.

$Q=\frac{[HCl]^2}{[CaCl_2]}=\frac{ 30.2^2 }{0.652 }=1398.8$

Thus, since Q>K, the reaction will shift leftwards, favoring the formation of reactants, therefore, answer is 3. The reaction will shift to the left.

Best regards.