Water

Question 1

Why do we sometimes have hosepipe bans in summer?

Answer 1

To conserve water

Question 2

Why is conserving water resources becoming increasingly important?

List 3 reasons I guess

Answer 2

1. World population increases
2. Water pollution issues
3. Global climate altering rainfall patterns (regions less rainfall)

Question 3

Explain the water purification process

Answer 3

Stage 1: Sedimentation
Allows large objects like branches or rocks (leaves and etc) to settle on bottom of reservoir. Take water from the top

Stage 2: Filtration
Removes small insoluble particles like sand or mud

Stage 3: Chlorination/Disinfection
Adds chlorine to kill bacteria

^^^ this is light work

Question 4

One advantage and disadvantage of fluoridation of drinking water

Answer 4

Advantage: helps to strengthen children’s teeth against decay
Disadvantage: high concentrations of fluoride make water poisonous and may cause cancer

Question 5

Describe process of desalination

Answer 5

1. Boil sea water in boiling chamber to evaporation
2. Cool the vapour and condense it back to a liquid
3. Removes salt or minerals from sea water

Question 6

Look at page 10 In ur water booklet

Answer 6

Okay

Question 7

What is hard water?

Answer 7

Contains calcium (or magnesium) compounds dissolved in it.
Compounds contain calcium ions, Ca^2+ (or magnesium ions, Mg^2+)

Question 8

What is temporary hard water?

And how to remove hardness?

Answer 8

Water containing soluble salt called hydrogen carbonate
(Rain water becoming acidic when co2 dissolves in it forming carbonic acid. Acid reacts with limestone (calcium carbonate) to form calcium hydrogen carbonate which is a soluble salt.)

Boiling it removes the hardness
(Dissolved calcium salt turns into calcium carbonate which is insoluble and precipitates out of solution as scale (limescale) )

Question 9

What is permanent hard water?

And how to remove hardness?

Answer 9

Water containing calcium sulphate
(Rainwater running through calcium containing rocks such as gypsum (calcium sulphate) then dissolves into the water.)

2 ways:
1. Add washing soda
(Sodium carbonate, Na2CO3, reacts with calcium ions to form calcium carbonate which is insoluble and comes out of solution as a solid thus removing calcium ions (Ca^2+) and the hardness)
Ca^2+(aq) + CO3^2+(aq) —-> CaCO3(s)

2. Using an ion exchange column
   (Suitable for large scale water treatment, swaps calcium ions for sodium ions as water runs through a column filled with a resin rich in sodium ions (Na^+) )

Question 10

How to test if water is hard?

Does water contain dissolved Ca^2+ ions?

Answer 10

Add soap solution to water and shake.
Soap lathers immediately = water is soft
Soap doesn’t lather + forms scum = hard

Question 11

How to test what type of hardness the water is?

Answer 11

Boiling it and testing it with soap solution

It’s temporary hardness if it’s hardness is already removed from boiling

Question 12

3 advantages and 3 disadvantages of hard water?

Answer 12

Advantages:
· Calcium ions (Ca^11?) are good for teeth and bones
· Hard water tastes nicer
· Reduces heart diseases and helps reduce constipation

Disadvantages:
· Causes limescale
· Devices take longer to heat the water = more energy, high energy bill
· More soap needed to form lather

Question 13

Difference between temp and perm hard water?

formula ver.

Answer 13

Perm = Ca^2+ or Mg^2+ ions
Temp = HCO3 / Ca^2+

Question 14

What’s scum?

Why does it form?

Answer 14

Grey solid forming on the surface.

Calcium ions reacting with soap.

Question 15

How would u show that a colourless liquid is pure water including the result you would expect?

Answer 15

Heat the water and check the temp it boils

Question 16

How can soap solution be used to determine how much hardness is present in a sample of hard water?

Answer 16

Test how many drops of soap it takes to form a lather

Question 17

What’s dissolved in water to make it hard?

Answer 17

Calcium and magnesium ions

Question 18

How does hardness of water vary from place to place?

Answer 18

Different types of rocks in different places

Question 19

Difference if used a small amount of soapless detergent?

Answer 19

Can’t see any soap scum

Question 20

Describe an investigation you would carry out using soap solution to identify what water samples are which
(one is permanent hard water, one was temporary hard water, one was distilled water)

this is like learning process of digestive system :(

Answer 20

1. Add 10cm^3 of each water sample to a test tube
2. Add droplets of soap until a permanent lather is formed (by shaking 10 times)
3. Soft water would need least amount of soap
4. Perm + temp would require more soap than soft water
5. Boil both and repeat step 2 on both water’s
6. Now temp water requires less soap

Question 21

A reason why energy may be wasted in homes in hard water areas?

Answer 21

Devices will take more time to heat water when limestone is present.
^^^ = energy being wasted

Question 22

What are separating techniques used for?

Answer 22

Separate mixtures of substances into pure substances

Different methods depend type of mixture u gat

Question 23

What does a condenser do?

Answer 23

Condenses vapour back into a liquid

Question 24

What’s filtration for?

Not water process treatment

Answer 24

Separating an insoluble solid from a liquid

Question 25

What’s chromatography for?

Answer 25

Separating dissolved substances that have different colours, such as inks and plant dyes.

Good cuz coloured substances dissolve in the liquid better than others travelling further up paper :0000

Question 26

Be good at analysing graphs

especially when ya gotta point out differences and similarities

Answer 26

Thanks, good luck bro

Question 27

Look at page 33

Answer 27

Ok fine :(