LO: to explain how Britain came into existence as continents, how different climates Britain has experienced and magnetic clues that geologists

use to track continents

C3 Journey through Time

Starter: What are the three main layers of the Earth called?

Movement of ChangeEarth’s outer layer is made of tectonic plates, these plates move because of very slow convection currents in the underlying solid mantle.

Movements of the tectonic plates cause oceans to open up slowly between continents in some parts of the world. Plate movements bring continents together with great force, creating mountain ranges. Major volcanic eruptions and earthquakes happen at plate boundaries.

Magnetic PastTo confirm this scientists used magnetic particles in the rock to track the position of north and south of the Equator.

Volcanic lava and sediments contain mineral magnetite.

The mineral gets its name from magnetic properties of its crystal. Magnetite can be magnetised in a fixed direction once the rock has cooled enough.

The magnetisation line up in the direction of the Earth’s magnetic field at the time. Near the Equator, the magnetisation lies horizontally, nearer to the Poles, the magnetisation is at an angle to the horizontal.

By measuring the angle at which crystals are magnetised in rocks, scientists can work out the latitude at which the rock was originally formed.

The evidence supported continental drift and development of the theory of plate tectonics.

1) What causes continents to move over the surface of the Earth?

2) Do the observations of magnetic minerals made by the scientists at Imperial College

support or conflict with the theory of plate tectonics?

3) Suggest evidence that geologists might look for to test the theory that the northern and

southern parts of Britain were once on different continents.

LO: to explain how Britain came into existence as continents, how

different climates Britain has experienced and magnetic clues

that geologists use to track continents

Review Learning:

Moving rocks 7th JuneAim• To describe why different rocks provide evidence for plate tectonics

Use the picture and labels provided to join up the correct name and part of the Earth’s structure.Once you have completed the task above, write a little bit about each

part.

Starter

Continental drift

Ring of fire

Plates move in a specific direction....

Which 3 different ways is it possible for the plates to move...with respect to each other??

Look at the arrows.

Constructive boundary

The recent volcanic ash cloud in Iceland ruined flights for months...

Destructive boundary

The Nazca plate is moving beneath the South American

plate. This pushes the continental crust upwards.

Conservative boundaryPacific plate meets

the North American plate

Modelling sedimentary rock

This beaker is similar to the one Mr Johnson is holding.

Using your common sense, discuss and agree on suitable answers to the

questions above.Write your answers in your books

BEAKER

WATER

SAND

Origin of rockProduces chalk (calcium

carbonate) which is a compound found in bones

and shells.

Swamp areas

Desert areas

Warm oceans

Produces coal (mainly carbon). Plant matter can be

changed into coal if the conditions prevent it rotting.

Produces red sandstone when deposited via

wind and rain.

Compasses...what’s the point?Which direction does your compass point?

Why do all compasses point this way?

THIS HAS SOMETHING TO DO WITH THE EARTH AND WHAT THE COMPASS IS MADE OF

Is there any way of changing the was a compass points?

USE THE MAGNET PROVIDED TO SHOW WHAT HAPPENS WHEN YOU GET NEAR TO IT

Are rocks magnetic??

LO: to explain what geologists can learn by studying can learn by studying rocks and the

origins of some of the rocks in Britain

Minerals in Britain

Starter: What are the three different types of rock? What

are their properties?

Clues in RocksGeologists can use the Earth’s surface to explain the history. Sedimentary rocks contains grains and these can be compared and geologists can tell how the rock was made by the shape and size.

Fossils of plants and animals can tell us about the life on the planet at different geological time.

British MineralsA chemical industry based on chlorine grew by the River Mersey because underground salt deposits, coal mines and lime stone quarries were nearby. These provided the raw material for making chlorine. The salt, coal and limestone formed at different times and different climates of Britain’s long geological history.

1) Give an example to show how studying a natural process today can tell scientists that processes such as

rock formation and mountain building are very slow and take place over

millions of years.

2) The chemical industry uses limestone quarried in the Peak District National Park because it is very pure. How do geologists account for the purity of

the limestone.

LO: to explain what geologists can learn by studying can learn

by studying rocks and the origins of some of the rocks in Britain

Review Learning:

LO: to explain how alkalis were first manufactured on a large scale, why this was such a polluting process and how Parliament

began to regulate the chemical industry

Chemicals from Salt

Starter: complete the following reactions:1) Hydrochloric acid + sodium hydroxide

2) Nitric acid + sodium hydroxide3) Potassium carbonate + sulphuric acid

Alkali IndustryDuring the 1700s there was a huge demand for alkalis.

In 1791, Nicolas Leblanc invented a new process that used chalk or limestone (calcium carbonate), salt (sodium chloride) and coal to make the alkali sodium carboante.

In England , Widnes and Runcorn, became the areas where this was produced due to the salt.

Leblanc ProcessThe process was highly polluting as solid waste was produced. It also released hydrogen chloride gas into the air.

This acidic gas devastated the land around and the solid waste dumped outside the factory slowly gave off a steady stream of toxic hydrogen sulphide gas.

RegulationsDuring the 1800s, industries grew and the British public demanded action from Government to control the pollution.

Pollution became so bad that in 1863, Parliament passed the first of the Alkali Acts. This Act set up an Alkali Inspectorate who travelled the country to check that at least 95% of acid fumes were removed from the chimneys of chemical factories.

They would dissolve the hydrogen chloride in water, this was released into water systems and it killed all the life .

In 1874, Henry Deacon invented a way to use the gas. He found that it was possible to oxidise hydrogen chloride to chlorine which can then be used to bleach (bleach paper and textiles).

He mixed hydrogen chloride with oxygen and let the two gases flow over a hot crystal. The products produced were chlorine and gas.

LO: to explain how alkalis were first manufactured on a large

scale, why this was such a polluting process and how

Parliament began to regulate the chemical industry

Review Learning:

LO: to explain the used of alkalis, where alkalis used come from and the reaction of neutralisation of acids with alkalis

Alkalis

Starter: What is neutralisation?

AlkalisThese can be used for;• neutralising acid soils• convert fats and oils to soap• making glass• make chemicals that bind natural dyes to cloth

AlumAlum is used for dyeing cloth, it helps the dyes to cling fast to the cloth, so that the colours did not fade too quickly during washing.

It was made on the north-east coast of Britain, where rock from the cliffs is rich in aluminium compounds. The rock was roasted in open-air fires for many months. Then they tipped the burnt rock into pits of water and stirred the mixture with long wooden poles.

The rock is then settled, the solution of soluble chemicals into lead pans. There they boiled the liquid to get rid of the water and added an alkali to neutralise acids in the solutions. The solution was cooled in wooden casks. Crystals formed and they would be crushed for sale.

Potash was one of the alkali used, this is ash of burnt wood. Others were ammonia from stale urine.

Reactions• alkalis are soluble in water• when dissolved they raise the pH of water above 7• they neutralise acids• two very corrosive alkalis are sodium hydroxide and potassium hydroxides• when they neutralise with acids, salt and water are produced

Acid + Alkali Salt Water+

1) At which stages of the manufacture of alum were the following process involved? Which processes involved

chemical reactions to make new chemicals?a) Oxidation

b) dissolving c) Evaporation

d) Neutralisation e) Crystallisation

2) Stale urine contains 2g of ammonia in 100 cm3 of the liquid. The daily output of a person is about 1500 cm3

of urine. f) Estimate the mass of ammonia, in tonnes, that could be

obtained per person per year (1 tonne = 1000 kg = 100g)

g) 3.75 tonnes of ammonia is needed to make 100 tonnes of alum. Estimate the number of people needed to supply the urine for an alum works producing 100

tonnes of alum per year.

LO: to explain the used of alkalis, where alkalis used come from

and the reaction of neutralisation of acids with

alkalis

Review Learning:

pH of soil can be changed by adding alkali (lime)

Ash from burnt plants was used as an alkali source... So was urine from people’s homes

Ashes of seaweed and lime were mixed with sand to make glass.

Plant dyes (alkali) mixed with alum, made the colour stick

Making limeThe lime we use to neutralise soil can be made using calcium carbonate.

If we heat up calcium carbonate (CaCO3) in a boiling tube, it decomposes (which means no chemicals react with it, just heat turns it into new products).

In this reaction, lime (chemical name is calcium oxide, or CaO) is produced and a gas is given off.

To do:

1) Write a word equation for this decomposition reaction. (You’ll need to have a guess at the name for the gas given off)

2) Write a balanced symbol equation for this reaction.

LO: to be able to explain why there is a need to check on the safety of a very large number of

chemicals, the European Union’s programme for testing and the problem of persistent harmful

chemicals

Protecting Health and Environment

Starter: List as many Chemical Safety

Symbols as you can

Flammable

Toxic

Explosive

Corrosive

Harmful (h) or Irritant (i)

Oxidising

Dangerous to the Environment

Untested ChemicalsWorld Wide Fund for Nature (WWF) and Greenpeace are fearful of synthetic chemicals. The campaigners have highlighted evidence suggesting that chemicals, such as those found in plastics and pesticides, may cause cancer, or lead to defects in new-born babies.

Scientists who study toxic chemicals agree that some commonly used synthetic chemicals can be harmful in large doses, but in concentrations found in bodies.

1) Give a chemical example to explain the difference

between a hazard and risk.

2) Why can’t scientists say for sure that small traces of permitted chemicals are

completely safe?

REACHIn 2007, the EU introduced the REACH system to collect information about the hazards of chemicals and to assess the risks.

REACH switches most of the responsibility for control and safety of chemicals from the authorities to the companies that make them, or use them. Now industry has to manage the risks of chemicals for human health and tee environment.

Manufacturers and importers will pay for most of the cost of REACH. The cost for the whole EU

will be about 5 billion Euros over the first 11 years of the testing programme. The EU has a

population about 500 million people;

a) Do you think that such a large cost is justified?

b) Is it right that industry should have to organise and pay for the testing? Explain your

answer.

POPs and PollutionThere are some synthetic chemicals that do not break down in the environment for a very long time. This means they can spread widely around the world in air and water. They build up in the fatty tissues of animals.

This set of chemicals is sometimes called the ‘dirty dozen’. They are;

• eight pesticides (DDT and DDE)• two types of compounds used in industry (PCBs)• two by-products of industrial activity (dioxins)

The ‘dirty dozen’ are classified as persistent organic pollutants (POPs). Many of the compounds contain chlorine.

They are a problem for the Arctic, where traditional diets are often high in fat. POPs tend to accumulate in fatty tissue of animals.

At a Convention in Stockholm (2001) it was agreed to deal with POPs. It was effective in 2004 and 150 countries have agreed to outlaw the ‘dirty dozen’.

Suggest reasons why Stockholm convention allows the use of the insecticide DDT to control mosquitoes in parts of the world

where malaria so a serious problem.

LO: to be able to explain why there is a need to check on the

safety of a very large number of chemicals, the European Union’s programme for testing and the problem of persistent harmful

chemicals

Review Learning:

LO: to be able to explain the chemical used to plasticise PVC and to be able to explain the risks

of PVC and how they are regulated

Benefits and Risks of Plasticisers

Starter: what is a plasticiser?

ToymakersToymakers like to use PVC because it very versatile:

• can be rigid or flexible• mixed with pigments to give bright colours

• stands to rough play• easy to keep clean

Worries of PlasticisersPlasticisers are chemicals that make PVC soft and flexible. The most common plasticisers for PVC are phthalates.

They are made of small molecules, which can escape from the plastic and dissolve in liquids that are in contact with it. They can also leach out of the plastic used to make blood bags or intravenous drips and so enter patient’s bodies.

There is no evidence or known case of anyone ever having been harmed from the use of phthalates.

EU RegulatorsThe EU has restricted two common phthalate plasticisers to toys that cannot be placed in the mouth. A third DEHP has been completely banned.

PVC with DEHP was used in medical devices. Though it would leach into liquids. There are alternatives but they are expensive.

Why does it makes sense for regulators to ban the use of the DEHP in toys, but only to issue warnings

and advice about the use of medical equipment made with PVC softened with the same plasticiser?

1) Why is it so hard to prove that there is no risk when people have fears

about possible dangers from a chemical?

2) If alternatives to DEHP became available, how might this affect

decisions by hospitals about which material to use?

LO: to be able to explain the chemical used to plasticise PVC

and to be able to explain the risks of PVC and how they are

regulated

Review Learning:

LO: to be able to explain what the life cycle assessment is in terms of the product and the

impact the product has

Life Cycle Assessment

Starter: what happens to a plastic bottle?

Products LifeThe life of each of these products has four distinct phases;

1. The materials are made from natural raw materials

2. manufacturers make products from the materials3. people use them4. people throw them away

Wood – biodegradable so it would rot

Glass, metal and plastics – last forever, not sustainable (they

had a life but not a cycle)

Nan’s TV

Life Cycle AssessmentManufacturers can assess what happens to he materials in their products. This LCA is part of legislation to protect the environment.

The aim is to slow the rate at which we use up natural resources that are not renewable. At each stage energy is used.

An LCA involves collecting data about each stage in the life of the product. It includes the use of materials/water, energy inputs and outputs, and environmental impact.

Compare the LCA of wooden window frames against PVC window frames.

Plastic Frame

Wooden Frame

1) Choose a product that has been designed to reduce its impact on

the environment.a) Describe the product

b) Explain how its environmental impact has been reduced.

2) Give two reasons why it is not a good idea to put products in

landfill once we have used them.

LO: to be able to explain what the life cycle assessment is in terms of the product and the

impact the product has

Review Learning: