How to Make Dry Calcium Carbonate in the Laboratory

One method for the preparation of dry calcium carbonate (CaCO₃) in the laboratory is by reacting calcium chloride (CaCl₂) with sodium carbonate (Na₂CO₃) in aqueous solution. This reaction results in the formation of solid calcium carbonate and aqueous sodium chloride. Reaction equation: CaCl₂ (aq) + Na₂CO₃ (aq) → CaCO₃ (s) + 2 NaCl (aq) Steps for preparation: 1. Preparing the solutions: Dissolve a known amount of calcium chloride and sodium carbonate separately in two different beakers containing distilled water. Make sure both the reactants are dissolved completely. 2. Mixing the reactants: Slowly pour the sodium carbonate solution into the calcium chloride solution, while continuously stirring. This mixing causes the formation of a white precipitate of calcium carbonate. 3. Filtration: Filter the mixture through a filter paper using a vacuum filtration setup, such as a Buchner funnel, to separate the solid calcium carbonate from the liquid Sodium Chloride solution. The precipitate collected on the filter paper is the calcium carbonate. 4. Washing: Wash the collected calcium carbonate with distilled water to remove any residual sodium chloride. This step is important to remove impurities and ensure the purity of the resulting calcium carbonate. 5. Drying: Transfer the wet calcium carbonate onto a clean watch glass or petri dish, and then allow it to air-dry in an area free from dust or any contaminants. Alternatively, you can place the wet calcium carbonate in a desiccator or a drying oven set at a low temperature (around 40°C) to expedite the drying process. After drying, the obtained solid is the dry calcium carbonate. 6. Storage: Store the dry calcium carbonate in a tightly sealed container to prevent it from absorbing moisture or reacting with carbon dioxide present in air, as calcium carbonate reacts with CO₂ and water to form calcium bicarbonate.