C3.2 Water Flashcards Preview

GCSE Chemistry AQA > C3.2 Water > Flashcards

Flashcards in C3.2 Water Deck (14):
1

How is hard water produced from rain water?

calcium/magnesium ions dissolve
from rocks (limestone)

2

What is formed when hard water reacts with soap

scum

3

State one health benefit of drinking hard water

-helps maintain bones
-helps maintain teeth
-helps reduce heart disease

4

Why is distillation generally not used to purify water

High cost of energy

5

Why is chlorine added to water

-kill microbes
-sterilise it

6

What in water filters reduce the hardness of water

Ion exchange column

7

Suggest why water filters contain particles of nanosilver

-kill microbes
-sterilise it

8

Describe the main two steps used to treat water from reservoirs

-filter
-to remove solids
-add chlorine
-to kill bacteria/sterilise it

9

A student boils some hard spring water in a pan.
The inside of the pan becomes coated with a white solid.
Explain how the white solid is produced.

-water contains calcium hydrogen carbonate (HCO3-)
-which decomposes
-to form calcium carbonate (or limescale)

10

Explain how an ion exchange column softens water

-Sodium ions (Na+) in the resin
-replace
-calcium ions(Ca2+)/magnesium ions (Mg2+)

11

Why do some companies add fluoride to the drinking water?

-Improve dental health (reduce tooth decay)

12

Describe how sodium carbonate is used to soften water

-sodium carbonate is added to hard water
-calcium ions precipitate out (form a solid)
-as calcium carbonate
-which can be filtered out of the water

13

How is scale formed?

-temporary soft water is heated
-hydrogen carbonate ions decompose
-to form carbonates

14

People who use hard water can expect higher costs than people who use soft water.
Explain why.

either
Forms scum
more soap is needed to form a lather

or

forms scale on heating
making kettles/heating systems less efficient