C3.2 Flashcards
Why is the water we drink not pure
Because it contains dissolved substances
What water is safe to drink
Water that has been treated
What does treated water mean
Water that does not contain anything that could cause us harm
What do the dissolved substances make the water
Hard and beneficial to our health
What is difference between hard water and soft water in terms of soap
Soft water readily forms lather with soap and hard water reacts with soap to form scum so more soap is needed to form lather
What does not form scum
Soapless detergent
What does hard water contain
Dissolved compounds usually calcium or magnesium
When do calcium and magnesium become dissolved in the water
When water comes into contact with rocks
What are the two types of hard water
Permanent
Temporary
What is the difference between permanent and temporary hard water
Permanent hard water remains hard when it is boiled and temporary hard water is softened by boiling
What does temporary hard water contain and what can it do
Hydrogen carbonate that can can decompose by heating to produce carbonate ions which react with calcium and magnesium ions to form precipitates
Why can hard water increase cost
More soap is needed to make a lather
What can temporary hard water produce in a kettle and heating systems
Limescale that reduces the efficiency.
What are the benefits of hard water
Calcium is good for development and maintenance of bones and teeth and help reduce heart disease
How can hard water be made soft
Removing the dissolved calcium and magnesium ions
