2021 · Q17
When calcium metal reacts with sulphuric acid, the reaction stops after a short while. Why?
general-sciencechemistry
- AThe reaction of calcium with sulphuric acid is not feasible at room temperature
- BFormed calcium sulphate is insoluble in water and covers the calcium metal, preventing it from reacting any further
- CFormed calcium sulphate requires two molecules of water to crystallize as gypsum
- DFormed calcium sulphate is unstable
Explanation
When calcium reacts with sulphuric acid, calcium sulphate is formed as a product. Unlike magnesium sulphate, calcium sulphate is insoluble in water, so it deposits as a coating on the surface of the calcium metal. This coating physically separates the metal from the acid and prevents further reaction, so the reaction stops after a short while. Hence the insolubility of the formed calcium sulphate is the reason.