Question

A copper complex reacts with ammonia according to the following reaction, where the left side of the reaction is a pale sky-blue color and the right side is dark blue.

Cu(H2O)2+4(aq)+4NH3(aq)⇌Cu(NH3)2+4(aq)+4H2O(aq)


Which change to a solution at equilibrium will make the solution darker?

(1 point)

adding Cu(NH3)2+4
salt

adding water ( H2O
)

removing ammonia ( NH3
)

removing Cu(NH3)2+4
salt

Answer 1

Removing the Cu(NH3)4^2+ salt.

By Le Chatelier’s principle, removing the dark-blue product shifts the equilibrium right to produce more Cu(NH3)4^2+, increasing the dark-blue complex. (Adding Cu(NH3)4^2+, adding H2O, or removing NH3 would shift the equilibrium left, making the solution lighter.)