Flashcards in C3.2 Water Deck (20):
What ions does hard water contain?
calcium and magnesium
Does soft water form a lather easily?
Does hard water form a lather easily?
What is scum?
the result of the dissolved ions in hard water and the soap
Where does the calcium and magnesium come from?
when streams and rivers flow over calcium or magnesium rocks
Where does the calcium come from?
carbon dioxide dissolves into the rain making it acidic so streams become acidic too and when reacted with calcium carbonate in rocks, forms calcium hydrocarbonate which is dissolvable in water
How does hard water waste soap?
more water for the same amount of soap
What is scale?
the insoluable substance formed when temporarily hard water is heated
Why is scale bad?
with scale, a kettle takes longer to boil so more energy is needed so it is more expensive
Advantages of drinking hard water
calcium ions help develop teeth and bones, reduce heart disease
what is temporary hardness?
hard water which is softened when boiled
What is permanent hardness?
hard water whose calcium and magnesium ions are not removed when the water is boiled
How can you soften hard water?
with an ion-exchange column and by using washing soda (sodium carbonate)
How do ion-exchange columns work?
filled with resins of sodium and the calcium and magnesium ions exchange with them but must be topped with salt to restore sodium ions
How do we make water safe to drink?
By adding chlorine which kills the microbes
How to clean water in filters?
Carbon reduces the levels of chlorine, pesticides and organic impurities, ion-exchange resin removes metal ions, silver discourages the growth of bacteria
What is distilled water?
Why do we not drink pure water?
takes lots of time and energy to make it pure and filtered water is fine
Why fluorisationf of water is good
no harmful effects, good for teeth, reduce heart disease, small amount anyway