Question

Which of the following reactant pairs will not react together to produce a reaction? Li + H2O Fe + Ni(OH)2 Ca + ZnF2 Co + BaCl2

Answer 1

You can use an activity series table (or a reduction potential table) to determine whether or not the reaction will go through. Before you do that you need to identify what is to be oxidized and what is to be reduced.

For example, we wanna know if: \(\sf Co_{(s)} + BaCl_2 \rightarrow CoCl_2+Ba_{(s)}\) will go forward.

From an activity table, we see that Ba is MORE reactive than Co. This means that Ba will not oxidize Co and the reaction will NOT go through.

Answer 2

Anyways its not 1,2 and 3 bcos Li lies above H, Fe lies above Ni and Ca lies above Zn in the reactivity series. A more reactive metal can replace a less reactive metals...

so I guess Co will be less reactive than Ba and hence the reaction wont take place.