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Flashcards in C3 Deck (41):

How do geologists explain most of the past history of the surface of the earth?

Through the processes that can be observed today


What has moved over time that means that parts or Britain today were once part of ancient continents on different part of the Earth?

Tectonic plates


How can geologists use magnetic clues in rocks?

They use them to track the very slow movement of the continents over the surface of the earth


Rocks formed on the equator will have an angle magnetism of what?

zero degrees


What is erosion?

The wearing away of rock


What is sedimentation?

When small pieces of material fall to the bottom of a body of water and settle at the bottom


How is coal formed?

The remains of dead trees and plant were buried in sediments that were pushed deeper underground until the effects of pressure and heat turned them into coal.


How is limestone formed?

The deposition of hard mineral remains of sea creatures and chemically is mainly calcium carbonate.


How is salt formed?

Salts are dissolved in water from the rock faces and can then later be exposed due the evaporation of water in shallow seas


What four pieces of evidence can geologist use to find evidence of the conditions under which which rocks were formed?

1. Fossils
2. Shapes of grain
3. The presence of shell fragments
4. Ripples from the sea or river bottom


Why did chemical industries grow in north west England?

The were large deposits of salt, coal and limestone there.


Identify three ways in which salt is useful to different groups of people ?

1. Food industry
2. As source of chemicals
3. To treat icy road in winter


Which two places can slat be obtained from?

The sea or from underground salt deposits


Identify two different ways that underground salt can be obtained?

1. Mining (physically digging it up)]
2.Solution mining


How might obtaining salt have an impact on the environment?

Extracting salt in solution can create large underground caverns , which could collapse and lower the Earth's surface aka subsidence.


Give two advantages of adding slat to food.

As a flavour enhancer and as a preservative


How might eating too much salt affect health?

Increases blood pressure , leading to risk of heart attack and stroke


What is the role of Defra? (Department of Environment, Food and Rural Affairs)

They carry our risk assessments in relation to chemicals in the food and advise the public in relation to the effect of food on health


Before industrialisation what were alkalis needed for?
Name four reasons

To neutralise acidic soil
Make chemical to bind dyes to cloth
convert fats and oils into soap
Manufacture glass


Identify two traditional sources of alkali

Burnt wood or stale urine


What two products are always formed from a reaction between alkali and an acid?

A salt and water


What types of chemicals are classified as alkalis?

Soluble hydroxides and carbonates


Metal hydroxide + acid =

Salt + water


Metal carbonate + acid =

Salt + carbon dioxide + water


What led to a shortage of alkali in the nineteenth century?

Increased industralisation


Describe the first process for manufacturing alkalis( Leblanc process) and the waste produced

Sodium chloride was mixed with sulphuric acid and heated with charcoal and limestone.This created the alkali sodium carbonate. and waste gas hydrogen chloride which was toxic.


How were the waste products of the Leblanc process made useful?

The hydrogen chloride was dissolved in water to create hydrochloric acid and it could also be oxidised to form chlorine


Recall two uses of chlorine

To kill micro-organisms and in bleach


What are the benefits of adding chlorine to drinking water?

Treating water with chlorine kills micro-organisms : reduces the risk of public getting water-borne diseases.Bettering their health


What are the possible disadvantages of chlorinating drinking water?

Chlorine can react with organic matter in the water to form THMs. These may cause cancer.(possibility)


How is chlorine obtained currently?

By the electrolysis of brine


What are the products in the electrolysis of brine?

Sodium hydroxide, Chlorine and Hydrogen


Give two uses for Chlorine?

Disinfectant and making plastics


Give two uses of sodium hydroxide?

Processing food products and manufacturing paper


Give two uses of hydrogen?

Potential as a pollution free fuel and manufacturing hydrochloric acid


How can some toxic chemicals (such as pops) cause problems to people and wildlife?

Because they take long to break down they can be carried over large distances in air and water. POPs accumulate in the fatty tissues of animals, including humans. Exposure to POPs can lead to illness and in severe cases death


What elements does the polymer PVC contain?

Chlorine, carbon and Hydrogen


Why might plasticisers in PVC have harmful effects?

They leach out from the plastic into surroundings


What are the four main stages of a life cycle assessment?

1. making the material from raw materials
2.making the product from the raw material
3.Using the product
4.Disposing of the product


What are the three main considerations for each stage of a life cycle?

1.Use of resources( including water )
2.The energy input or ouput
3.The environmental impact


What are the three main considerations for each stage of a life cycle?

1.Use of resources( including water )
2.The energy input or output
3.The environmental impact