Review the description of the hydrated copper complex below.

Question

Use this model to respond to the following multiple choice question set.

Which condition below would shift the system in dynamic equilibrium to dark blue?

(1 point)
Responses

Adding ammonia
Adding ammonia

Removing water
Removing water

Removing the hydrated copper complex [Cu(H2O)2+4]

Question 3.

If the system is at dynamic equilibrium, what will be the color result if an acid is added to the system?

(1 point)
Responses

Blue
Blue

Light blue
Light blue

Dark blue
Question 4.

Concerning the addition of an acid tot he system. Select 2 reasons why the color change could result.

(2 points)
Responses

The reaction between the acid and the base produces extra water which would reverse the reaction.
The reaction between the acid and the base produces extra water which would reverse the reaction.

Adding an acid removes ammonia, the base, so the reaction reverses to replace it.
Adding an acid removes ammonia, the base, so the reaction reverses to replace it.

Adding an acid adds positive ions which favors the forward reaction.
Adding an acid adds positive ions which favors the forward reaction.

Adding an will heat up the system favoring a reverse shift.

Answer 1

Let's break down the questions and analyze them based on the information provided about the hydrated copper complex.

Question 1:

Which condition below would shift the system in dynamic equilibrium to dark blue?

Responses:

1. Adding ammonia
2. Removing water
3. Removing the hydrated copper complex [Cu(H2O)2+4]

Correct Answer: Adding ammonia
Reasoning: In the presence of ammonia, the equilibrium shifts towards the formation of the dark blue complex [Cu(NH3)4]²⁺. Adding ammonia increases its concentration, which will favor the forward reaction and lead to a darker blue color.

Question 2:

If the system is at dynamic equilibrium, what will be the color result if an acid is added to the system?

Responses:

1. Blue
2. Light blue
3. Dark blue

Correct Answer: Light blue
Reasoning: Adding acid typically increases the concentration of hydrogen ions (H⁺), which can cause the equilibrium to shift back towards the hydrated copper complex ([Cu(H2O)2+4]), resulting in a lighter blue color compared to the dark blue complex formed in the presence of ammonia.

Question 3:

Concerning the addition of an acid to the system. Select 2 reasons why the color change could result.

Responses:

1. The reaction between the acid and the base produces extra water which would reverse the reaction.
2. Adding an acid removes ammonia, the base, so the reaction reverses to replace it.
3. Adding an acid adds positive ions which favors the forward reaction.
4. Adding an will heat up the system favoring a reverse shift.

Correct Answers:

• 2. Adding an acid removes ammonia, the base, so the reaction reverses to replace it.
• 1. The reaction between the acid and the base produces extra water which would reverse the reaction.
  (though typically it’s the removal of ammonia that directly influences the shift)

Reasoning: Adding acid will compete with ammonia, effectively depleting it in the system, thus shifting the equilibrium to favor the formation of the hydrated copper complex, which is lighter in color. The production of water (if the acid is a strong acid and reacts) can also influence the equilibrium, but the primary factor here is the removal of ammonia.

Overall, the addition of acid results in a light blue solution due to these shifts in equilibrium.