Write out the balanced equation for the reaction that occurs when Mg and Fe(NO3)3 react together.

Question

anonymous · Answer

it will be substition betwin $$Fe ^{3+}   and      Mg ^{2+}$$

sleepyjess · Answer

@Abhisar

abhisar · Answer

Have you learnt about substitution reaction?

sleepyjess · Answer

No, I have learned double replacement

sleepyjess · Answer

Here is the example they gave, Cu + 2AgNO3 $\rightarrow$ Cu(NO3)2 + 2Ag, so would it be Mg(NO3)3 + Fe?

sleepyjess · Answer

That is what I am thinking, but I am probably wrong :(

abhisar · Answer

You are correct about skeleton structure of the equation. When you write the chemical formula of a compound like when you write $\sf Fe(NO_3)_3$, you actually write the valency of each radical in the subscripts i.e 3 after the brackets in the subsript in $\sf (NO_3)_3$ represents the valency of Fe. Similarly valency of $\sf NO_3$ is written in the subscript in Fe. When no subscript is mentioned it means that the valency is 1 so the valency of $\sf NO_3$ is 1

Now the skeleton structure of our equation as you said is following

$\sf Mg + Fe(NO_3)_3 \rightarrow Mg(NO_3)_\color{red}{?}+Fe$

Replace the ? with correct valency.

sleepyjess · Answer

Wouldn't it be 3?

abhisar · Answer

How?

Whose valency is 3?

sleepyjess · Answer

No, 2

sleepyjess · Answer

$\sf Mg + Fe(NO_3)_3 \rightarrow Mg(NO_3)_\color{red}{2}+Fe$

abhisar · Answer

Again how/why?

sleepyjess · Answer

I'm not really sure, that was just one of the examples they gave in the lessons, but didn't explain it at all :(

abhisar · Answer

Just explain what made you think it should be 2 so that I can know if you have understood it properly.

sleepyjess · Answer

Because that is the number of valence electrons gained?

abhisar · Answer

Read what I said you earlier again. To write a chemical formula say $\sf Fe(NO_3)_3$ you just criss cross the valencies as following

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