C3 Flashcards
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?
- Fossils
- Shapes of grain
- The presence of shell fragments
- 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 ?
- Food industry
- As source of chemicals
- 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?
- 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?
- making the material from raw materials
- making the product from the raw material
- Using the product
- Disposing of the product
What are the three main considerations for each stage of a life cycle?
- Use of resources( including water )
- The energy input or ouput
- The environmental impact
What are the three main considerations for each stage of a life cycle?
- Use of resources( including water )
- The energy input or output
- The environmental impact
