Question

Write the balanced chemical equations of the following word equation:
Potassium dichromate + sulphuric acid $ \to $ potassium sulphate + chromium sulphate + water + oxygen

Answer 1

Hint:A balanced chemical reaction is a reaction which has equal numbers of atoms of each element on both sides of an equation. A balanced chemical equation follows the law of conservation of mass. To answer this question, you must recall the chemical formulae for each of the given compounds and then balance the number of atoms on each side of the reaction.

Complete answer:
From the law of conservation of mass, we know that matter can neither be created nor destroyed and nor can one element change into the other in a chemical reaction, thus the amount of each element must be the same throughout the entire reaction. For example, the number of atoms of any element in the reactants will be always equal to the number of atoms of that element in the products formed.
Potassium dichromate as the name suggests contains one potassium ion and two dichromate ions. Its chemical formula is ${K_2}C{r_2}{O_7}$
We know the chemical formula of sulphuric acid as ${H_2}S{O_4}$
Both potassium sulphate and chromium sulphate are sulphate salts. Sulphate ion carries a charge of $ - 2$. Their chemical formulae are ${K_2}S{O_4}$ and $C{r_2}{\left( {S{O_4}} \right)_3}$ respectively.
The skeletal equation for the given word equation
Potassium dichromate + sulphuric acid -> potassium sulphate + chromium sulphate + water + oxygen can be written as:
${K_2}C{r_2}{O_7} + {H_2}S{O_4} \to {K_2}S{O_4} + C{r_2}{\left( {S{O_4}} \right)_3} + {H_2}O + {O_2}$
On balancing the number of each atom on both sides of the reaction using hit and trial method, we can finally write the balanced chemical equation as:
$2{K_2}C{r_2}{O_7} + 8{H_2}S{O_4} \to 2{K_2}S{O_4} + 2C{r_2}{\left( {S{O_4}} \right)_3} + 8{H_2}O + 3{O_2}$

Note:
A skeletal equation is an unbalanced chemical equation and does not follow the law of conservation of mass. It just denotes the reaction occurring but not the amount of the chemicals used or produced.