Question

Write the balanced chemical equations for the following reactions and identify the type of reaction in each case.

(a) nitrogen gas is treated with hydrogen gas in the presence of a catalyst at $773\mathrm{K}$ to form ammonia gas.

Answer 1

Balanced chemical equation:

• A chemical equation is a symbolic statement of any chemical reaction where the reactants and products are replaced by their chemical formulae and symbols.
• A balanced equation involves an equal number of atoms for each element on the reactant and product side.

Word equation to symbolic equation:

• The skeletal chemical equation is as follows:-
  ${\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{N}}_2\left(\mathrm{g}\right)\to {\mathrm{NH}}_3\left(\mathrm{g}\right)$

Balancing the Chemical Equation:

• We will tabulate the number of atoms of each element on the reactant as well as on the product side.

Element	Reactant side	Product Side
H	2	3
N	2	1

• From the table, it is clear that the Atoms of Hydrogen and nitrogen are not balanced.
• For balancing the atoms we will make the coefficient of ${\mathrm{NH}}_3$ as $2$ and ${\mathrm{H}}_2$ as $3$. The equation becomes,
  $3{\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{N}}_2\left(\mathrm{g}\right)\to 2{\mathrm{NH}}_3\left(\mathrm{g}\right)$
  

Element	Reactant side	Product Side
H	6	6
N	2	2

• The chemical equation is balanced.
• Since both Hydrogen and Nitrogen combine to form ammonia, implies the above reaction is an example of a combination reaction.
  

Hence, the final balanced chemical equation is $3{\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{N}}_2\left(\mathrm{g}\right)\to 2{\mathrm{NH}}_3\left(\mathrm{g}\right)$.