C3.2 Water Flashcards Preview

GCSE Chemistry > C3.2 Water > Flashcards

Flashcards in C3.2 Water Deck (20):
1

What ions does hard water contain?

calcium and magnesium

2

Does soft water form a lather easily?

yes

3

Does hard water form a lather easily?

no

4

What is scum?

the result of the dissolved ions in hard water and the soap

5

Where does the calcium and magnesium come from?

when streams and rivers flow over calcium or magnesium rocks

6

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

7

How does hard water waste soap?

more water for the same amount of soap

8

What is scale?

the insoluable substance formed when temporarily hard water is heated

9

Why is scale bad?

with scale, a kettle takes longer to boil so more energy is needed so it is more expensive

10

Advantages of drinking hard water

calcium ions help develop teeth and bones, reduce heart disease

11

what is temporary hardness?

hard water which is softened when boiled

12

What is permanent hardness?

hard water whose calcium and magnesium ions are not removed when the water is boiled

13

How can you soften hard water?

with an ion-exchange column and by using washing soda (sodium carbonate)

14

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

15

How do we make water safe to drink?

By adding chlorine which kills the microbes

16

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

17

What is distilled water?

pure water

18

Why do we not drink pure water?

takes lots of time and energy to make it pure and filtered water is fine

19

Why fluorisationf of water is good

no harmful effects, good for teeth, reduce heart disease, small amount anyway

20

Why fluorisation of water is bad

weakens bones, no significant benefit to teeth, haven't consented, lead to learning difficulties, can't control people's intake