1.3 - Water

Question 1

Dissolved ions in water

Answer 1

Sodium, Calcium, Magnesium, Sulfate, Chloride, Hydrogencarbonate

Question 2

Dissolved gasses in water

Answer 2

Oxygen, Carbon dioxide

Question 3

Pollutants in water

Answer 3

Chemical fertilisers, pesticides, animal waste

Question 4

Ways to conserve water

Answer 4

Shorter showers, fix leaky taps, turn off taps when not in use

Question 5

Water abstraction methods

Answer 5

Pumping water from underground, dams and reservoirs, collecting rainwater

Question 6

Reasons why people dislike reservoirs

Answer 6

Destroy habitats, changes the appearance of an area

Question 7

Water treatment

Answer 7

Sedimentation, Filtration, Chlorination

Question 8

Sedimentation

Answer 8

Large insoluble particles settle to the bottom of the tank, clean water is extracted from the top of the tank

Question 9

Filtration

Answer 9

Water is sprayed onto layers of sand and gravel, smaller insoluble particles are removed

Question 10

Chlorination

Answer 10

Chlorine gas is injected into the water and it kills the microorganisms

Question 11

Fluoridation

Answer 11

The addition of small amounts of fluoride to drinking water to prevent tooth decay

Question 12

Why does fluoride help tooth decay ?

Answer 12

Alters the structure of developing enamel in young children so its resistant to reacting with acid, Reduces the ability of plaque bacteria to form acid

Question 13

Negatives of fluoride

Answer 13

Dental fluorosis, 90% of toothpaste and mouthwash has high levels of fluoride, mass medication

Question 14

Desalination

Answer 14

The removal of salt from water

Question 15

Reverse osmosis (Desalination)

Answer 15

Seawater is forced through a membrane at high pressure, only water is able to pass through

Question 16

Thermal desalination

Answer 16

Water evaporates, water Vapor is collected and condensed, Salt left behind

Question 17

Disadvantages to desalination

Answer 17

Requires lots of energy, expensive, Releases lots of greenhouse gases

Question 18

Why is desalination popular in the Middle East ?

Answer 18

Low rainfall, Lots of coastlines, wealthy countries

Question 19

Saturated solution

Answer 19

No more solute can be dissolved

Question 20

Soluble

Answer 20

Able to dissolve in water

Question 21

Solvent

Answer 21

The liquid in which the solute dissolves into

Question 22

Solute

Answer 22

The solid dissolving

Question 23

Solubility shown

Answer 23

Grams of solute per 100g of water

Question 24

Effect of temperature on solubility

Answer 24

Solids are more soluble as temperature increases

Question 25

Ions in hard water

Answer 25

Magnesium (Mg2+), Calcium (Ca2+)

Question 26

How does water become hard ?

Answer 26

Water comes into contact with limestone or other rocks containing calcium compounds

Question 27

Remove temporary hardness

Answer 27

Boiling

Question 28

Problems caused by limescale

Answer 28

Coating heating elements in kettles making them less efficient, clogging hot water pipes

Question 29

Cause of temporary hardness

Answer 29

Dissolved calcium hydrogencarbonate

Question 30

Is rainwater acidic or alkaline ?

Answer 30

Acidic

Question 31

What happens when temporary hard water is boiled ?

Answer 31

The calcium hydrogen carbonate decomposes to form calcium carbonate, water and carbon dioxide

Question 32

Cause of permanent hard water

Answer 32

Dissolved calcium sulfate

Question 33

Advantages of hard water

Answer 33

Taste, Calcium helps children’s teeth and bones, reduces heart disease

Question 34

Disadvantages to hard water

Answer 34

Hard to lather, Waste soap, Limescale

Question 35

Measuring hardness

Answer 35

Soap lather test

Question 36

Ways to soften permanent hard water

Answer 36

Washing soda, Ion exchange columns

Question 37

How does washing soda work ?

Answer 37

The large amount of carbonate ions in washing soda react with the dissolved calcium ions in water, forming calcium carbonate

Question 38

How do ion exchange columns work ?

Answer 38

Water is run through a column containing resin, the calcium and magnesium ions get stuck to the resin, sodium ions swap places with the calcium and magnesium ions

Question 39

Resetting ion exchange columns

Answer 39

Run salt water through it