# How would you identify the missing coefficient in the balanced equation and classify the type of reaction?

## $M g {\left(O H\right)}_{2} + {H}_{2} S {O}_{4} \to M g S {O}_{4} + {H}_{2} O$

May 23, 2017

$\text{Mg(OH)"_2 "(s)"+ "H"_2"SO"_4 "(aq)" -> "MgSO"_4 "(aq)"+ color(blue)(2)"H"_2"O(l)}$

#### Explanation:

In order for the reaction to be balanced, the number of atoms of each element must be equal on both sides of the reaction arrow. On the left side, we have

$\text{Mg} : 1$
$\text{O} : 2 + 4 = 6$
$\text{H} : 2 + 2 = 4$
$\text{S} : 1$

And on the right side,

$\text{Mg} : 1$
$\text{O} : 4 + 1 = 5$
$\text{H} : 2$
$\text{S} : 1$

You'll notice that the products side is short two hydrogens and one oxygen. Coincidentally, $\text{H"_2"O}$ just so happens to have that exact element ratio. We need one more $\text{H"_2"O}$ molecule on the products side to balance this equation, so its coefficient becomes

$1$ (understood, not shown) + $\textcolor{red}{1} = \textcolor{b l u e}{2}$

The balanced chemical equation is thus

$\text{Mg(OH)"_2 "(s)"+ "H"_2"SO"_4 "(aq)" -> "MgSO"_4 "(aq)"+ color(blue)(2)"H"_2"O(l)}$

This type of reaction is a special kind of double-replacement reaction (or metathesis reaction) called a neutralization reaction, in which an acid and a base react in aqueous solution to form a salt and (usually liquid) water.

May 23, 2017

$M g {\left(O H\right)}_{2}$ + ${H}_{2} S {O}_{4}$ => $M g S {O}_{4}$ + $2 {H}_{2} O$

Metathesis Reaction or, Double Replacement Reaction or, Acid Base Reaction or, Ion Exchange Reaction.

#### Explanation:

There are two primary classifications of reactions
1. Oxidation-Reduction Reactions
2. Metathesis Reactions

Oxidation-Reduction Reactions are characterized by a change in oxidation states of the elements in the reaction.

Metathesis Reactions are Ion Exchange Reactions of the form
AX + BY => AY + BX where A, B, X & Y are Ions in aqueous solution. For a Metathesis Ion Exchange Reaction to occur, a product is formed that leaves the reaction system as a solid precipitate, soluble weak acid or weak base or a gas decomposition product. The Metathesis Reactions reaction is characterized by NO CHANGE in oxidation states of elements in the reaction process.