Question

When potassium metal is placed in water, a large amount of energy is released as potassium hydroxide and hydrogen gas are produced in the reaction 2K(s) + 2H2O(l) → 2KOH(aq) + H2(g). Your lab partner says this is a redox reaction and a combustion reaction. Do you agree? Defend your answer by explaining whether or not it meets the requirements of each type of reaction.

Answer 1

Since you're asking this question, I will assume that you don't know what a redox reaction or a combustion reaction is.

A redox reaction, or an oxidation-reduction reaction, is a reaction that involves the transfer of electrons. While one reactant gets oxidized (loses electrons), another reactant gets reduced (gains electrons).

Do you know how to assign oxidation states to the different elements so that we can see if and what got oxidized/reduced?

Answer 2

Also, a combustion reaction involves a reactant, usually a hydrocarbon, reacting with oxygen gas (\(\text{O}_2\)) to release energy. The products of the reaction are \(\text{CO}_2\) and \(\text{H}_2\text{O}\).

Knowing that, do you think that your reaction is a combustion reaction?