Use the reaction to answer the question.

Question

Cr O (aq) + H O(l) ⇄ 2CrO (aq)+ 2H (aq)
Given Cr O ions are orange and CrO ions are yellow, which change to the reaction would most effectively make the solution more
orange?
(1 point)
2 7
2–
2 4
2– +
2 7
2–
4
2–
increasing the pH
removing water
adding water
decreasing the pH

Answer 1

To make the solution more orange, you would want to favor the formation of \( Cr_2O_7^{2-} \) ions, which are orange.

Looking at the reaction:

\[ Cr_2O_7^{2-} (aq) + H_2O (l) ⇄ 2 CrO_4^{2-} (aq) + 2 H^+ (aq) \]

To shift the equilibrium to the left (favoring \( Cr_2O_7^{2-} \)), you can decrease the concentration of \( CrO_4^{2-} \), which is yellow, or increase the concentration of \( H^+ \) ions (decreasing the pH).

Therefore, the most effective change to make the solution more orange would be:

Decreasing the pH.