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AP® Chemistry

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Moderate

Temperature Change

APCHEM-71OUED

Consider the equilibrium:

$$[Co(H_2O)_6]^{2+}(aq) \text{ (pink ion) } + 4 Cl^-(aq) ⇄ [CoCl_4]^{2-} (aq) \text{ (blue ion) } + 6 H_2O(l)$$

The equilibrium constant for the reaction is $1 × 10^{-3}$ at 276 K and $1 × 10^8$ at 353 K.

Which of the following is TRUE about this reaction if it was conducted in a sealed vessel put on ice until the temperature of the solution reaches close to 0$^o$C?

A

Endothermic.

The solution would look blue.

B

Endothermic.

The solution would look pink.

C

Exothermic.

The solution would look blue.

D

Exothermic.

The solution would look pink.