Question

Question #1057d

Answer 1

`2"Mg"("NO"_ 3)_ (2(s)) -> 2"MgO"_ ((s)) + "O"_ (2(g)) + 4"NO"_ (2(g))`

Explanation:

Start by writing the unbalanced chemical equation that describes the decomposition of magnesium nitrate

`"Mg"("NO"_ 3)_ (2(s)) -> "MgO"_ ((s)) + "O"_ (2(g)) + "NO"_ (2(g))`

Now, notice that you have `2` atoms of nitrogen on the reactants' side and only `1` on the products' side.

To balance out the nitrogen, multiply the nitrogen dioxide molecules by `2`. This will get you

`"Mg"("NO"_ 3)_ (2(s)) -> "MgO"_ ((s)) + "O"_ (2(g)) + 2"NO"_ (2(g))`

Next, focus on the oxygen. You have a total of `6` atoms of oxygen on the reactants' side and

`overbrace("1 O")^(color(blue)("from MgO")) + overbrace("2 O")^(color(blue)("from O"_2)) + overbrace("4 O")^(color(blue)("from 2 NO"_2)) = "7 O"`

on the products' side. To balance out the oxygen, multiply the oxygen molecule by `1/2`. This will get you

`"Mg"("NO"_ 3)_ (2(s)) -> "MgO"_ ((s)) + 1/2"O"_ (2(g)) + 2"NO"_ (2(g))`

The products' side will now have

`overbrace("1 O")^(color(blue)("from MgO")) + overbrace("1 O")^(color(blue)("from"color(white)(.)1/2"O"_2)) + overbrace("4 O")^(color(blue)("from 2 NO"_2)) = "6 O"`

Since you have `1` atom of magnesium on both sides of the equation, you can say that the balanced chemical equation that describes the decomposition of magnesium nitrate looks like this

`"Mg"("NO"_ 3)_ (2(s)) -> "MgO"_ ((s)) + 1/2"O"_ (2(g)) + 2"NO"_ (2(g))`

If you want, you can get rid of the Fractional coefficient by multiplying all the chemical species involved in the reaction by `2`

`2"Mg"("NO"_ 3)_ (2(s)) -> 2"MgO"_ ((s)) + (2 * 1/2)"O"_ (2(g)) + (2 * 2)"NO"_ (2(g))`

to get

`2"Mg"("NO"_ 3)_ (2(s)) -> 2"MgO"_ ((s)) + "O"_ (2(g)) + 4"NO"_ (2(g))`