Question

How would you balance ${{\text{H}}_{\text{3}}}{\text{P}}{{\text{O}}_{\text{4}}}{\text{ + Mg}}{\left( {{\text{OH}}} \right)_{\text{2}}} \to {\text{M}}{{\text{g}}_{\text{3}}}{\left( {{\text{P}}{{\text{O}}_{\text{4}}}} \right)_{\text{2}}}{\text{ + }}{{\text{H}}_{\text{2}}}{\text{O}}$

Answer 1

Hint: We know that a chemical is called a balanced chemical equation when the number of atoms of all elements is equal in both the product and reactant side of the reaction. While balancing a chemical equation we also need to equate charges if any charge is present.

Complete step by step answer:
Here, phosphoric acid reacts with magnesium hydroxide to form magnesium phosphate (salt) and water. This is an example of a neutralization reaction. The given chemical equation is,
${{\text{H}}_{\text{3}}}{\text{P}}{{\text{O}}_{\text{4}}}{\text{ + Mg}}{\left( {{\text{OH}}} \right)_{\text{2}}} \to {\text{M}}{{\text{g}}_{\text{3}}}{\left( {{\text{P}}{{\text{O}}_{\text{4}}}} \right)_{\text{2}}}{\text{ + }}{{\text{H}}_{\text{2}}}{\text{O}}$
To balance the above equation, first we add coefficient 3 to magnesium hydroxide to equate the number of magnesium on both sides of the reaction.
${{\text{H}}_{\text{3}}}{\text{P}}{{\text{O}}_{\text{4}}}{\text{ + 3Mg}}{\left( {{\text{OH}}} \right)_{\text{2}}} \to {\text{M}}{{\text{g}}_{\text{3}}}{\left( {{\text{P}}{{\text{O}}_{\text{4}}}} \right)_{\text{2}}}{\text{ + }}{{\text{H}}_{\text{2}}}{\text{O}}$
Now, we have to add coefficient 2 to phosphoric acid and 6 to water to equate the number of atoms of H, P and O.
${\text{2}}{{\text{H}}_{\text{3}}}{\text{P}}{{\text{O}}_{\text{4}}}{\text{ + 3Mg}}{\left( {{\text{OH}}} \right)_{\text{2}}} \to {\text{M}}{{\text{g}}_{\text{3}}}{\left( {{\text{P}}{{\text{O}}_{\text{4}}}} \right)_{\text{2}}}{\text{ + 6}}{{\text{H}}_{\text{2}}}{\text{O}}$
Now, the number of atoms of H, P, O, and Mg is equal in both sides of the reaction. So, the above chemical equation is balanced.

Note: When an acid undergoes reaction with a base, then the reaction is known as neutralization reaction. This reaction can be applied in our day to day life. For example, when an acidity problem occurs, we are advised to take antacid tablets. These tablets are actually bases which neutralize the effect of acid in the stomach.
It is to be noted that a chemical reaction needs to be balanced to follow the law of conservation of mass. According to this law, the creation or destruction of mass is not possible. So, the number of atoms present before the reaction must be equal to the number of atoms after the reaction.