Question

What is the net ionic equation of the reaction of FeCl2 with NaOH? Express you answer as a chemical equation including phases.

Answer 1

`Fe^(2+)(aq)+2OH^(-)(aq)->Fe(OH)_2(s)downarrow`

Explanation:

We first write down the balanced equation for this reaction:

`FeCl_2(aq)+2NaOH(aq)->2NaCl(aq)+Fe(OH)_2(s)downarrow`

This is a precipitation reaction, where two soluble salts are mixed together in solution forms to make a precipitate.

So, we can now write the ionic equation for this reaction, that is:

`Fe^(2+)(aq)+2Cl^(-)(aq)+2Na^+(aq)+2OH^(-)(aq)->2Na^+(aq)+2Cl^(-)(aq)+Fe(OH)_2(s)downarrow`

Now, we need to cancel the spectator ions, which are ions that are present on both sides in the equation. So, the equation becomes

`Fe^(2+)(aq)+color(red)cancelcolor(black)(2Cl^(-)(aq))+color(red)cancelcolor(black)(2Na^+(aq))+2OH^(-)(aq)->color(red)cancelcolor(black)(2Na^+(aq))+color(red)cancelcolor(black)(2Cl^(-)(aq))+Fe(OH)_2(s)downarrow`

The final net ionic equation is now:

`Fe^(2+)(aq)+2OH^(-)(aq)->Fe(OH)_2(s)downarrow`

The iron(II) hydroxide formed is easily oxidized when exposed to air and can easily become iron(III) hydroxide `(Fe(OH)_3)`.