Hard” water contains large amounts of metal ions, especially ions of calcium and magnesium, but also iron. Hard water is often described as having a metallic taste. These metal ions can form precipitates with some anions in the water. These precipitates can build up inside pipes or hot water heaters and cause plumbing problems.

Question

Hard” water contains large amounts of metal ions, especially ions of calcium and magnesium, but also iron. Hard water is often described as having a metallic taste. These metal ions can form precipitates with some anions in the water. These precipitates can build up inside pipes or hot water heaters and cause plumbing problems.

describe a chemical test you could perform to determine if a sample of water is “hard.” Be specific in the description of what you would add to the water and explain why. What would you expect to observe for a positive vs. a negative test?

Answer 1

Find a plastic or glass bottle with a tight fitting cap. Fill it about 1/3 full with tap water from the bathroom. Add several SMALL chips of soap (something like Castile soap; i.e., with no detergent or perfumes added). If no soap is available used liquid soap (not liquid detergent), shake thoroughly. Upon standing soft water will have lots of soap bubbles and the solution will be clear. Hard water will give a milky solution.