Materials chalk calcium hydroxide filter paper phenolphthalein heat source two Pyrex beakers Directions Crush some classroom chalk (a mixture of limestone and gypsum) finely. Mix chalk into water in a beaker. Pour the mixture through filter paper. The water appears to be "pure." Boil the water or let it evaporate away. What is left? Water also dissolves and transports minerals. In a beaker, mix calcium hydroxide and water. Filter until clear. Fill another container with water. Obtain some phenolphthalein solution and add a few drops to a glass of "pure" water. Add a few drops to the water mixed with calcium hydroxide. Give the results Explain the results.