Use the chemical equation to answer the question.

Question

Co(H O) + 4Cl + heat ⇄ CoCl + 6H O
Cobalt ions form complex ions with water and chloride. The Co(H O) ions are pink, and the CoCl ions are blue. A scientist creates
a solution that is purple at equilibrium. How can the scientist make the solution more pink?
(1 point)
2 6
2+ –
4
2–
2
2 6
2+
4
2–
by adding water (H O) 2
by adding Co(H O) ions 2 6
2+
by adding hydrochloric acid (HCl)
by adding heat to the system

Answer 1

To make the solution more pink, the scientist should shift the equilibrium to the left, towards the formation of the Co(H2O)6^2+ complex ions, which are pink. This can be achieved by increasing the concentration of the reactants or removing the products from the system.

Among the options provided, the ways to shift the equilibrium to the left include:

• By adding water (H2O): This would increase the concentration of the reactants, thus shifting the equilibrium to the left, favoring the formation of Co(H2O)6^2+ ions and increasing the pink color.

• By adding Co(H2O)6^2+ ions: This also increases the concentration of the reactant, shifting the equilibrium to the left and making the solution more pink.

Adding hydrochloric acid (HCl) would introduce more Cl^- ions, which would push the equilibrium to the right, making the solution more blue. Adding heat would also typically favor the side of the reaction that absorbs heat; if the reaction is endothermic (which can vary), this might also not favor the pink side.

The best answer to make the solution more pink would be:

By adding water (H2O).