C4: Air and Water

Question 1

% of Nitrogen in the air

Answer 1

78%

Question 2

% of Oxygen in the air

Answer 2

21%

Question 3

% of Argon in the air

Answer 3

0.9%

Question 4

% of Carbon Dioxide in the air

Answer 4

0.04%

Question 5

Nitrogen Boiling Point

Answer 5

-196 C

Question 6

Argon Boiling Point

Answer 6

-186 C

Question 7

Oxygen Boiling Point

Answer 7

-183 C

Question 8

How are the gases in the air separated in industry?

Answer 8

Fractional Distillation of Liquid Air

Question 9

Fractional Distillation of the Air Process

Answer 9

1. Compress the air to 150 times atmospheric pressure. This warms up the air, so it is then passes over cold water pipes)
2. Pressure is released, and air is allowed to expand rapidly. Causes temp to drop enough that the gases -> liquids. CO2 and H2O are removed easily as they are solid at this temperature.
3. Temp is slowly increased and the gases boil off one by one. Nitrogen - Argon - Oxygen

Question 10

O
I
L
R
I
G

Answer 10

Oxidisation is loss (of electrons)

Reduction is gain (of electrons)

Question 11

Bases

Answer 11

The oxide, hydroxide or carbonate of a metal that will react with an acid, forming a salt as one of the products.
Bases dissolved in water are alkalis.

Question 12

Amphoteric Metals

Answer 12

An oxide that displays both acidic and basic properties.

Question 13

Test for oxygen gases.

Answer 13

A glowing splint will relight in oxygen.

Question 14

Metal oxides are…

Answer 14

Basic

Question 15

Non-Metal oxides are…

Answer 15

Acidic

Question 16

3 elements of a water filter and their purposes.

Answer 16

> Carbon- Reduces chlorine in water
Ion-exchange resin- removes calcium, magnesium, lead, copper and aluminium.
Silve- Discourages the growth of bacteria in the filter.

Question 17

Desalination

Answer 17

The removal of salts from water to make it safe to drink.

Question 18

Positives of Fluoridation of Water.

Answer 18

> Reduces cavities.
Protects those with bad dental hygiene.
Protects from bacteria that causes heart disease.

Question 19

Negatives of Fluoridation of Water.

Answer 19

> Fluorosis- Weakens bones.
Benefit for teeth is not significant.
Ethically wrong- no consent from people.
Can cause learning difficulties and Alzheimers
Can’t control intake.

Question 20

Which metal rusts?

Answer 20

Iron

Question 21

What is needed for iron to rust?

Answer 21

Oxygen and Water.

Question 22

What prevents rusting?

Answer 22

> Paint
> Oil/ Grease
> Plastic
> Less reactive metal
> More reactive metal

Question 23

Galvanised

Answer 23

Iron or Steel objects that have been protected from rusting by a thin layer of zinc metal at their surface.

Question 24

Sacrificial Protection

Answer 24

An effective way to prevent rusting whereby a metal more reactive than iron (e.g zinc or magnesium) is attached to or coated on an object.