Final answer:
When potassium hydroxide (KOH) and cobalt(II) nitrate (Co(NO3)2) are mixed, a precipitate of cobalt(II) hydroxide (Co(OH)2) forms, due to its low solubility in water.
Step-by-step explanation:
When KOH (potassium hydroxide) is combined with Co(NO3)2 (cobalt(II) nitrate), a double-replacement reaction occurs, which may result in the formation of a precipitate if the resulting compounds have low solubility in water. The possible products of this reaction are KNO3 (potassium nitrate) and Co(OH)2 (cobalt(II) hydroxide).
According to solubility rules, KOH and KNO3 are soluble in water, but Co(OH)2 is not. Therefore, Co(OH)2 would precipitate out of the solution, forming a solid. The balanced chemical equation for this reaction is 2 KOH (aq) + Co(NO3)2 (aq) → 2 KNO3 (aq) + Co(OH)2 (s).