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How to Make an Aqueous Solution Out of Calcite

Aqueous solution refers to a water based solution. When you dissolve salt in water, you have created an aqueous salt solution. Calcite is one form of the minerals in CaCO3. Calcium carbonate precipitates in water under most conditions, however, it is possible to change the conditions and get it to dissolve in water. The dissolution of calcite is governed by two equilibriums involving carbon dioxide, water and calcite.

Things You'll Need

Beaker
Piece of calcite
Water
CO2 tank with delivery tube
Watch glass
Ice bath
6 M hydrochloric acid

Instructions

- 1
  Set up a beaker on the lab bench. Place a piece of calcite into the beaker and cover with water. It is obvious that the calcite didn't dissolve. Under the conditions of the laboratory environment calcite prefers the solid state.
- 2
  Secure the end of the delivery tube of a CO2 tank in the beaker and cover it with a watch glass large enough to cover the opening of the beaker. This configuration increases the concentration of CO2 in the immediate environment of the calcite. Increasing the concentration of CO2 in the atmosphere of the solution containing calcite favors the dissolution of calcite.
- 3
  Place the beaker in a water bath with ice to lower the temperature of the water in the beaker. Temperature affects the equilibrium of calcite in the solid form. Lower water temperatures favor calcite dissolution.
- 4
  Add 6 ml hydrochloric acid to the water in the beaker until the calcite dissolves in the water. Increasing the acid concentration shifts the pH of the solution. Allow enough time for the acid to shift the equilibrium between solid and solution form of calcite. Continue adding acid to the solution until you have dissolved the calcite to the desired amount.

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