Calcium chloride is an ionic compound with the chemical formula CaCl2. It dissolves readily in water. Its affinity for water is so great, in fact, that it's useful as a desiccant or drying agent. Calcium chloride is used primarily to de-ice roads; it also enjoys a number of uses in industry, and more than 1.6 million tons are produced in the United States each year. While calcium chloride is readily available commercially, it's fairly straightforward to prepare.
- Skill level:
Things you need
- 0.1 molar hydrochloric acid
- 2 beakers
- Fume hood
- Chemical splash goggles
- Lab coat
- Calcium carbonate
- Glass stirring rod
- Filter paper
Make sure you are wearing a coat, gloves and splash goggles before you begin this experiment, and perform it under the fume hood for safety.
Measure out 5 grams (0.176 oz.) of the calcium carbonate and add it to the first beaker.
Measure out 500ml of the 0.1 molar hydrochloric acid solution using the other beaker, and add it to the calcium carbonate beaker. Stir with the glass stirring rod. The solution should begin to bubble, since the reaction that takes place between the hydrochloric acid and the calcium carbonate is given by the following chemical equation:
CaCO3 + 2 HCL --> CO2 + CaCl2 + H2O, where the CO2 gas will escape while the CaCl2 remains in solution.
Wait until the solution has ceased to bubble. Note that there should still be some calcium carbonate left undissolved because the mixture you made included 0.05 moles of HCl and 0.05 moles of calcium carbonate, but each formula unit of calcium carbonate will react with two molecules of HCl; moreover, calcium carbonate is largely insoluble in water.
Pour the mixture through the filter paper to remove the remaining calcium carbonate. At this point the solution that passes through the filter paper should contain dissolved calcium chloride.
Tips and warnings
- Hydrochloric acid is a strong acid and a powerful skin and eye irritant; if ingested it is extremely toxic and can cause severe eye damage if splashed in your eyes. Always take proper precautions when working with hydrochloric acid.
- Don't assume the mixture you've produced is pure and therefore safe to ingest; it's never wise to make these kinds of assumptions.
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