A student adds the following stresses one at a time to separate samples of an equilibrium mixture of [Co(H2O)6]^2+ (pink) <-> [CoCl4]^2- (blue) + 6 H2O (delta H > 0 forward) and records color change: Trial A: heat the solution -> turns blue Trial B: add concentrated HCl -> turns blue Trial C: add AgNO3 -> turns pink Trial D: add water -> turns pink
Trial A confirms that the forward reaction is:
- A
non-spontaneous at all temperatures
- B
at equilibrium with K = 1
- C
exothermic, since heating shifts toward reactants
- Dcheck_circle
endothermic, since heating shifts the equilibrium toward products (blue)
Explanation
For an endothermic forward reaction, increasing T shifts to the right (products). Solution turning blue indicates more [CoCl4]^2-.