Hard and soft water Flashcards
Why is the water we drink not pure?
Because it contains dissolved substances
What is formed when soft water is combined with soap?
A lather
What is formed when hard water is combined with soap?
Scum
Usually what dissolved substances are in hard water?
Calcium or magnesium
Where does hard water pick up the compounds it contains?
Rocks
What are the two types of hard water?
Permanent and temporary
How do you soften temporary hard water?
By boiling it
What happens when permanent hard water is boiled?
It remains hard
What happens to the hydrogen carbonate ions in temporary water when its boiled?
They decompose on heating and produce carbonate ions which react with the calcium and magnesium to form precipitates
Why does using hard water increase the cost?
Because it requires more soap to form a lather
What is formed when temporary hard water is boiled that reduces the efficiency of a kettle?
Scale
What benefits does hard water have?
Good for the development of healthy bones and teeth
Reduce the risk of heart disease
What are the two ways of softening hard water?
- Reacting it with sodium carbonate which reacts with the calcium and magnesium ions to form a precipitate of magnesium and calcium carbonate
- Using and ion exchange resin which contains sodium or hydrogen ions that replace the calcium and magnesium ions when passed through the column
