Question

What happens when concentrated ${{H}_{2}}S{{O}_{4}}$ reacts to calcium fluoride?

Answer 1

Hint: To answer this question we should know the property of ${{H}_{2}}S{{O}_{4}}$ which is a strong acid. Calcium fluoride is an insoluble salt which is very sparingly soluble in water, but it dissolves in strong acids.

Complete Solution :
- Concentrated hydrochloric acid is a strong acid .We know that calcium fluoride is a very sparingly soluble that is an insoluble salt. Insoluble salts also dissolve in strong acids like concentrated sulphuric acid.
- Conc.${{H}_{2}}S{{O}_{4}}$ which is also a good sulfonating agent. So, it readily sulphonates any inorganic or organic compounds.
The reaction between white insoluble CaF and Conc.${{H}_{2}}S{{O}_{4}}$ which is liquid gives calcium sulphate and hydrofluoric acid.
\[Ca{{F}_{2}}+{{H}_{2}}S{{O}_{4}}\to CaS{{O}_{4}}+2HF\]

- The calcium sulphate is sparingly soluble in liquid but not very sparingly soluble like CaF.
When the concentrated sulphuric acid is added to calcium fluoride slowly the fumes will be coming out. These fumes are produced due to formation of HF which is a fuming acid. HF is a bit dangerous but it is used as refrigerants. $CaS{{O}_{4}}.2{{H}_{2}}O$ is known as gypsum is commonly known as plaster of paris which is used to make toys, fillers, to make plaster casts to immobilize broken bones.
- This reaction will not be that spontaneous and finding its rate constant is really tough . This comparatively slow reaction because an insoluble salts is reacted with liquid. It dissolves easily but not that fast that the reaction will be spontaneous.

Note: While writing the chemical equation for this reaction make sure that the chemical equation is balanced. The number of particular atoms in the reactant should be equal to the number of the same atom in product. If a chemical equation satisfies this above made statement then the reaction is said to be balanced. Sulphuric acid is known as the king of acids which acts as a dehydrating agent, oxidizing agent and sulfonating agent.