Chemistry

Question 1

What is a life cycle assessment?

Answer 1

An analysis of the overall environmental impact that a product may have throughout its lifetime

Question 2

What is distillation?

Answer 2

Purifying a liquid by heating and cooling

Question 3

What are the two processes for obtaining copper from low-grade copper ores?

Answer 3

• Using bacteria in a process called bioleaching
• Using plants in a process called phytomining

Question 4

What are the drawbacks of mining (Four)

Answer 4

• Visual pollution
• Sound pollution
• Increased traffic in the area
• Air pollution

Question 5

What are the TWO methods of obtaining copper from the ore

Answer 5

• Using sulfuric acid to produce copper sulfate solution, before extracting copper metal via displacement
• Heating the copper ore to a high temperature in a furnace with air to produce impure copper

Question 6

What are some of the general uses/needs for copper? (Three)

Answer 6

• Electrical wiring
• Construction
• Home appliances

Question 7

What happens during final treatment of sewage (Two stages)

Answer 7

• In the last tank, the useful bacteria are allowed to settle out to the bottom of the tank as sediment.
• Sometimes the water is filtered through a bed of sand, and then sterilised using UV

Question 8

What happens during primary treatment (sedimentation)?

Answer 8

The waste water is allowed to stand still in the tank. heavier solids sink to the bottom creating sewage sludge. The sludge is then removed

Question 9

What happens during screening? (Sewage)

Answer 9

Removes large objects using a large metal grid

Question 10

What is an ion?

Answer 10

A charged particle (can be negative or positively charged.

Question 11

What are the FOUR stages of sewage treatment

Answer 11

• Screening
• Primary treatment - sedimentation
• Secondary treatment - aerobic digestion
• Final treatment

Question 12

Process of salt water -> potable water (via Distillation)

Answer 12

Heated until it boils. The salt is still in the liquid but when the steam cools and condenses it is pure potable water (An expensive water)

Question 13

Process of salt water -> Potable water (Via osmosis).
And why is this more efficient in terms of energy?

Answer 13

Uses membranes to separate the water and salts dissolved in it. The membrane can catch 98% of dissolved salts.
- No heating required so uses less energy.

Question 14

What is desalination

Answer 14

converting salty water to potable water

Question 15

What are the physical properties of Group 7 elements (Three)

Answer 15

• At room temperature the physical state changes as you go down the group.
• The colours change as you go down the group.
• The melting points and boiling points change as you go down the group.

Question 16

What happens at the positive anode?

Answer 16

Negative anions lose electrons - they are oxidised

Question 17

What do these do in water?
1). Iron
2). Magnesium
3). Lithium
4). Sodium
5). Potassium

Answer 17

1). Iron - very slow reaction - some bubbles
2). Magnesium - Slow reaction - bubbles
3). Lithium - Fast reaction - floats, fizzes
4). Very fast reaction - floats, fizzes and forms a ball
5). Instant reaction - burns with a lilac flame, moves around

Question 18

What is an isotope?

Answer 18

Atoms of the same element with the same number of protons but DIFFERENT number of neutrons

Question 19

What do the symbols at the top and the bottom of an element mean

Answer 19

TOP: Relative atomic mass - protons + neutrons
BOTTOM: Atomic number: no. of protons

Question 20

What is chromatography?

Answer 20

This technique is used to separate substances that have a different solubilities

Question 21

What is the method of chromatography

Answer 21

• Pencil line is drawn on chromatography paper and spots of different ink are put on it.
• The paper is put into a beaker of water (the pencil line sits above the level of the solvent)
• The ink will spread across the paper showing the pigments

Question 22

What is an element?

Answer 22

A substance that is 100% pure - each element is made up of just one type of atom

Question 23

What are the properties of metals and non-metals FOUR

Answer 23

METALS
- Higher melting & boiling points - tend to be solids at room temperature
- Silver-coloured
- Good conductors
- Malleable (can be shaped)

NON-METALS
- Lower melting and boiling points
- More likely to be colourful
- Poor conductors of heat and electricity
- Brittle (They snap/smash easily)

Question 24

How is an ion made?

Answer 24

An ion is made when an atom loses or gains electrons to have a full outer shell of electrons

Question 25

What are the properties of the alkali metals? (Three)

Answer 25

• Silvery-coloured metals
• They are soft and could be easily cut with a knife
• They are highly reactive

Question 26

What was Ernest Rutherford’s theory?

Answer 26

By firing positively, charged alpha-particles at a gold sheet, he found that some passed through, while others deflected back. Rutherford had discovered the nucleus + disproved JJ Thomson.

Question 27

What model did these guys discover?
1). Ernest Rutherford
2). Niels Bohr
3). John Dalton
4). JJ Thompson

Answer 27

1). Nuclear model
2). Nuclear model 2.0
3). Solid sphere model
4). Plum pudding model