Question

Write the balanced equation for the following reaction

(a) Magnesium carbonate reacts with hydrochloric acid to produce magnesium chloride, carbon dioxide, and water.

Answer 1

Balanced chemical equation: A balanced chemical equation is the representation of a chemical reaction in which the number of atoms of each element is the same on both the reactant and product sides.

Word equation to symbolic equation:

• In the given reaction, Magnesium carbonate reacts with hydrochloric acid to produce magnesium chloride, carbon dioxide, and water.
• The chemical reaction can be represented as:

$\underset{\mathrm{Magnesium}\mathrm{carbonate}}{{\mathrm{MgCO}}_3\left(\mathrm{s}\right)}+\underset{\mathrm{Hydrochloric}\mathrm{acid}}{\mathrm{HCl}\left(\mathrm{aq}\right)}\to \underset{\mathrm{Magnesium}\mathrm{chloride}}{{\mathrm{MgCl}}_2\left(\mathrm{aq}\right)}+\underset{\mathrm{Carbon}\mathrm{dioxide}}{{\mathrm{CO}}_2\left(\mathrm{g}\right)}+\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$

Balancing the Chemical Equation:

Step 1: Write the number of atoms of each element

$\underset{\mathrm{Magnesium}\mathrm{carbonate}}{{\mathrm{MgCO}}_3\left(\mathrm{s}\right)}+\underset{\mathrm{Hydrochloric}\mathrm{acid}}{\mathrm{HCl}\left(\mathrm{aq}\right)}\to \underset{\mathrm{Magnesium}\mathrm{chloride}}{{\mathrm{MgCl}}_2\left(\mathrm{aq}\right)}+\underset{\mathrm{Carbon}\mathrm{dioxide}}{{\mathrm{CO}}_2\left(\mathrm{g}\right)}+\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$

Element	Reactant side	Product Side
$\mathrm{Mg}$	$1$	$1$
$\mathrm{C}$	$1$	$1$
$\mathrm{O}$	$3$	$3$
$\mathrm{Cl}$	$1$	$2$
$\mathrm{H}$	$1$	$2$

• From the table, it is clear that the atoms of Hydrogen and Chlorine are not balanced.

Step 2: Balancing the unbalanced atoms

• In order to balance the equation, we will make the coefficient of $\mathrm{HCl}$ as $2$.
• Now the equation becomes

$\underset{\mathrm{Magnesium}\mathrm{carbonate}}{{\mathrm{MgCO}}_3\left(\mathrm{s}\right)}+\underset{\mathrm{Hydrochloric}\mathrm{acid}}{2\mathrm{HCl}\left(\mathrm{aq}\right)}\to \underset{\mathrm{Magnesium}\mathrm{chloride}}{{\mathrm{MgCl}}_2\left(\mathrm{aq}\right)}+\underset{\mathrm{Carbon}\mathrm{dioxide}}{{\mathrm{CO}}_2\left(\mathrm{g}\right)}+\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$

Element	Reactant side	Product Side
$\mathrm{Mg}$	$1$	$1$
$\mathrm{C}$	$1$	$1$
$\mathrm{O}$	$3$	$3$
$\mathrm{Cl}$	$2$	$2$
$\mathrm{H}$	$2$	$2$

Hence, the balanced chemical equation is $\underset{\mathrm{Magnesium}\mathrm{carbonate}}{{\mathrm{MgCO}}_3\left(\mathrm{s}\right)}+\underset{\mathrm{Hydrochloric}\mathrm{acid}}{2\mathrm{HCl}\left(\mathrm{aq}\right)}\to \underset{\mathrm{Magnesium}\mathrm{chloride}}{{\mathrm{MgCl}}_2\left(\mathrm{aq}\right)}+\underset{\mathrm{Carbon}\mathrm{dioxide}}{{\mathrm{CO}}_2\left(\mathrm{g}\right)}+\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$