How to Dissolve Gypsum With HCL

A common fine-grained or white-tinted variety of gypsum is called alabaster.

Gypsum is a soft, pale, calcium-based mineral. When used in masonry and other construction work, it is often called plaster of Paris. Gypsum dissolves easily in a warm solution of dilute hydrochloric acid. Researchers use this method to dissolve gypsum in soils when the mineral is getting in the way of their soil research.

Things You'll Need

• 25 g of gypsum-containing soil sample
• 25 ml of a 2M solution of hydrogen chloride
• 500 ml water
• Electric stirrer
• Beaker
• Goggles
• Gloves

Instructions

1. Put the soil sample in the beaker, and add 25 millileters of 2M hydrogen chloride.

2. Add 500 millileters of water.

3. Use the electric stirrer on the mixture for a full hour. Allow it to clear and decant. Sparse crystals of gypsum should appear on the sides of the beaker.

4. Continue shaking and decanting until no further gypsum crystals can be seen.

Tips & Warnings

• Hydrochloric acid is a corrosive agent. Always wear protection for your eyes and hands when handling it.

References

• Food and Agriculture Organization of the United Nations: Laboratory Methods for Analysing Gypsiferous soils: Section 6.3.2
• Mindat.org: Gypsum
• University of Arizona Department of Geology: Gypsum
• Colorado University: Laboratory Safety