Question

Write the chemical formula and hence balance the following word equation:

$\mathrm{Magnesium}+(\mathrm{V}.\mathrm{dil}.)\mathrm{Nitric}\mathrm{acid}\to \mathrm{Magnesium}\mathrm{Nitrate}+\mathrm{Hydrogen}$

Answer 1

The given word equation is $\mathrm{Magnesium}+(\mathrm{V}.\mathrm{dil}.)\mathrm{Nitric}\mathrm{acid}\to \mathrm{Magnesium}\mathrm{Nitrate}+\mathrm{Hydrogen}$

The Symbol equation for this word equation is $\mathrm{Mg}+{\mathrm{HNO}}_3\to \mathrm{Mg}{\left({\mathrm{NO}}_3\right)}_2+{\mathrm{H}}_2$.

The balancing of the equations is done in the following steps :
Let us count the number of atoms of all the elements in the reactants and products on both sides of the equation.

Element/ion	No. of atoms of reactant(L.H.S)	No. of atoms of products(R.H.S)
$\mathrm{Mg}$	1	1
$\mathrm{H}$	1	2
${\mathrm{NO}}_3$	1	2

Thus, the number of 'Mg' atoms are equal on both sides. At the same time, the number of 'H' and ${\mathrm{NO}}_3$ ions are not equal.

On inspection, To balance the atoms, put coefficient 2 before ${\mathrm{HNO}}_3$ on the reactant side.

The partially balanced equation may be written as

$\mathrm{Mg}+2{\mathrm{HNO}}_3\to \mathrm{Mg}{\left({\mathrm{NO}}_3\right)}_2+{\mathrm{H}}_2$

On final inspection, the number of atoms of all the elements on both sides of the equation is equal. Therefore, the equation is balanced.