Ocr 21St Century Science C3

Front 1

Structure of the Earth

Back 1

Iron & nickel core, mantle, crust

Front 2

Tectonic plates

Back 2

Crust and upper mantle are cracked into large pieces called tectonic plates. They move around- few cm per year

Front 3

What shows the movement of tectonic plates?

Back 3

Magnetic clues in rocks. When tectonic plates move apart under the sea, exposed mantle rises up and a new crust solidifies.

New crust is magnetised by Earth's magnetic field. Normal or reverse polarity.

pattern of normal/reversed polarised rocks used to estimate age of parts of crust

Track slow movement of plates

Front 4

Sedimentary rocks contain clues

Back 4

Look at features of rocks. Fossils- remains/imprints of dead organisms tells age of rock. Conditions it was formed in.

Shells, ripples,shapes of grains (water-borne or air-blown)

Front 5

Minerals in the crust- formed by different processes

Back 5

Sedimentation, Evaporation, Dissolving, Erosion, Mountain building.

Chemical industries grow.

Front 6

Describe Limestone

Back 6

-Sedimentary rock from seashells

-over millions of years layers of sediment get buried. Weight pressing down squeezes out water

-natural mineral cement

Front 7

Describe coal

Back 7

-Black in colour

-Sedimentary

-Mainly carbon

-lots of impurities

Front 8

Where is salt found?

Back 8

Rock salt- salt and impurities, found in underground deposits.

Massive deposits in Cheshire & Teeside, UK

Front 9

What is normal salt mining?

Back 9

Physical extraction of salt

Rock salt is drilled, blasted, dug out, brought to surface.

Mostly used on roads to stop ice forming.

- salt can be seperated- flavour food, making chemicals

Front 10

What is solution mining?

Back 10

Water is injected into salt deposit.

Dissolves to make brine.

Pressure forces brine to surface.

Brine stored in wells and pumped to refining plant.

Impurities removed.

Brine boiled, water evaporates, salt left.

Most table salt, chemical production.

Front 11

How do these methods of mining salt impact the environment?

Back 11

Pollution- mining requires a lot of energy.

Subsidence- land above collapse into holes

Risk reduced by filled in caverns.

Front 12

Another method of obtaining salt

Back 12

in hot countries, evaporating seawater.

Shallow pools, left in sun, salt is collected.

Purest salt- almost 100% NaCl

Front 13

How is salt used in food production?

Back 13

To enhance flavour. Mostly in processed foods.

As a preservative- when added to meat, kills bacteria

Front 14

What are health issues with the use of salt?

Back 14

High intake= High blood pressure, stroke, heart attacks

Increases risks of stomach cancer, osteoporosis, renal failure.

Front 15

Government issues guidelines for salt intake

Back 15

Watchdogs, Food Standards agency.

GDA

risk assessments, advise the public.

Food manufactures still include salt to support sales. Cost of reformulating recipes is great.

Front 16

How is salt important for the chemical industry?

Back 16

They electrolyse brine- they pass an electric current through it.

Causes chemical change- splits solution into Hydrogen, Chlorine and Sodium Hydroxide.

Front 17

Electrolysis of Brine- 1) Chlorine

What are the uses?

Back 17

Disinfectants

Killing bacteria

Household bleach

Plastics

HCL

Insecticides

Front 18

Uses of hydrogen

Back 18

ammonia

turning oils into fats- margarine

fuels

welding and metal cutting

Front 19

Uses of Sodium Hydroxide

Back 19

Very strong alkali

Soap

Ceramics

Organic chemicals

Paper pulp

Oven cleaner

Household bleach- when it reacts with Chlorine.

Front 20

Environmental impact of large scale electrolysis

Back 20

Pollution

Uses finite resources

Mercury and asbestos are used- they are toxic, can cause cancer, contaminate rivers

Front 21

Chlorine used for water treatment

Back 21

small amounts added to water to kill bacteria

Prevents algae growth

kills disease causing microorganisms

Front 22

Why is chlorine important for water treatment?

Back 22

it lowers death rates- less people die from water-bourne diseases.

Over 1bn dont have access to clean water- very expensive.

Chlorine increases life expectancy.

V important.

Front 23

What are the disadvantages of chlorinating water?

Why do people object?

Back 23

Chlorine reacts with compounds to form chlorinated hydrocarbons- carcinogenic.

Chlorine gas irritates respiratory system.

Liquid chlorine causes severe chemical burns.

Some say we dont get a choice- forced 'mass medication'

Front 24

What are Alkalis?

Back 24

Type of chemical.

A compound that forms hydroxide ions when dissolved in water.

Front 25

What is a neutralisation reaction?

Back 25

Acid and an alkali react to form a salt and water.

The products are neutral.

Front 26

What are 2 types of neutralisation reactions?

Back 26

Acid+ Hydroxide= Salt + water

Acid + Carbonate= Salt + water + carbon dioxide

Front 27

What are the uses of alkalis?

Back 27

Farmers use alkalis to neutralise acidic soils.

Make chemicals for natural dyes.

Convert fats and oils into soap.

Manufacture glass.

Front 28

'History' of alkalis

Back 28

Used for hundreds of years.

People relied on traditional sources- burnt wood & stale urine.

19th Century- Shortage

Front 29

The LeBlanc Process

Back 29

Alkalis had to be manufactured on a large scale.

Process invented to make sodium carbonate.

Sodium chloride mixed with sulfuric acid then heated with charcoal and limestone.

Front 30

Problems of the LeBlanc Process

Back 30

Very Polluting.

Large volumes of acidic hydrogen chloride- damaged environment.

A lot of solid waste.

Released toxic Hydrogen Sulfide. Foul smell of rotten eggs.

Front 31

Products made using Chemistry

Back 31

Drugs, paints, dyes, used in industry, used in the home. agricultural chemicals, plastics, metals, fuels.

So many chemicals- Cannot be tested thoroughly. Not enough data about risks.

Front 32

Problems with toxic chemicals

Back 32

Stay in environment if not broken down.

End up in water ways/ eaten by animals.

Spread over large area.

Passed along food chains.

Harm to animals, even humans

Front 33

How can pesticides be harmful?

Back 33

1) Insecticide seeps into river 2) small plants take it in 3)Tiny animals eat the plants 4) Small fish eats tiny animals 5) Eel eats small fish 6) Otter eats eels

Toxic to creatures.

Front 34

How are plasticisers harmful?

Back 34

Leach out into water sources. Also toxic.

Front 35

Life Cycle Assessments- Stage 1

Back 35

Choice of material:

Water mostly needed. Metals mined and extracted. Lots of energy= pollution.

Raw materials- No- renewable and finite. E.g: Crude oil: finite and causes lots of pollution.

Front 36

LCA- Stage 2

Back 36

Manufacture:

Lots of energy.

Pollution: CO, HCl.

How to dispose/ recycle.

Front 37

LCA - Stage 3

Back 37

Using the product-

can also damage environment.

Paint; toxic fumes

Burning; greenhouse gases

Fertilisers; can leech out, damage ecosystem

Front 38

LCA- Stage 4

Back 38

Product Disposal:

Landfill site.

Takes up space, pollutes.

Might be incinerated(burnt); air pollution

Some can be recycled- processed & re- used