Question

What happens when concentrated ${\mathrm{H}}_2{\mathrm{SO}}_4$is added to Calcium Fluoride?

Answer 1

1. When Concentrated ${\mathrm{H}}_2{\mathrm{SO}}_4$is added to Calcium Flouride, the formation of solid Calcium Sulphate and the fumes of gaseous Hydrogen fluoride take place.
2. However, we know that Conc. ${\mathrm{H}}_2{\mathrm{SO}}_4$is a strong acid that readily reacts with an insoluble ${\mathrm{CaF}}_2$salt and forms sulphonates. Thus sulphuric acid is also called a Sulphonating agent.
3. The gas $\mathrm{HF}$formed is a very dangerous gas also used as a refrigerant.
4. This reaction is a very slow reaction due to the reaction of insoluble salt with a liquid.

$$\begin{gathered} {\mathrm{CaF}}_2\left(\mathrm{s}\right)+{\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{l}\right)\to {\mathrm{CaSO}}_4\left(\mathrm{aq}\right)+2\mathrm{HF}\left(\mathrm{g}\right) \\ \mathrm{Calcium}\mathrm{Calcium}\mathrm{Hydrogen} \\ \mathrm{Flouride}\mathrm{Sulphate}\mathrm{Flouride} \end{gathered}$$