Module C3 - Chemicals In Our Lives Flashcards
Why has Britain been located on different parts of the surface of the Earth?
Because most of the plates move a few cm each year so Britain is moving, relative to all other countries, around the Earth.
Why does the Earth’s oceanic crust have patterns of normal polarity and reversed polarity magnetised rock?
When tectonic plates move away from each other under the se, the exposed mantle rises up through the sea floor and solidifies to form new crust. This is magnetised by the Earth’s crust.
What different features of rocks can geologists look at to learn about the environment where they were formed?
Fossils tell you about the conditions where it was formed, for example, a fossil of a fish tells you it was formed underwater. The sediment that forms the rocks will either have been carried by water or air; the shape of grains will tell you whether it was formed on the surface (air blown grains) or whether it was formed underwater (water-borne grains).
List three processes by which minerals are formed.
Sedimentation. Evaporation. Erosion.
How is limestone formed?
From layers of sediment laid down in lakes or seas. The sediment can come from bones of sea creatures or from the erosion of pre-existing rocks. Over millions of years, the sediment layers get buried under more layers and the weight pressing down squeezes out the water. Fluids flowing through pores in the sediment will deposit natural mineral cement and this holds together the sediment particles to form rock.
What is a coal made from?
Carbon. It is formed by the fossilisation of layers of plant matter.
What is rock salt?
A mixture of salt and impurities that is found in underground deposits.
Describe the process of normal salt mining? What is this salt used for?
It is drilled, blasted and dug out and brought to the surface by machinery. It is used on roads when it is icy, but it is also used for making chemicals and for flavouring food.
Describe solution mining. What is this salt used for?
Water is injected into the salt deposit, through the outer pipe, which dissolves the salt to make a saltwater solution called brine. Pressure forced the brine to the surface, through the inner pipe, and the bribe is stored in wells above the surface and pumped to a refining plant when it is needed. Impurities are removed from the brine in the refining plant and its pumped into containers. The brine is then boiled to make the water evaporate, leaving salt behind. This rock is used for flavouring food and it is used in chemical production.
How can mining have an impact on the environment?
Subsidence can take place - the land above disused mines can collapse into the holes, which can affect buildings near the mines. It also used a lot of energy which comes from the burning of fossil fuels, which causes pollution.
How is salt used in food production?
It can enhance the flavour. It is used as a preservative, so the food will last longer.
What are the health issues surrounding salt?
It can cause high blood pressure which may lead to a heart attack or a stroke. It also increases the chances of getting stomach cancer, osteoporosis or renal failure.
Why is salt electrolysed when it is used in the chemical industry?
Salt is sodium chloride. When the salt solution, called brine, is electrolysed, it splits the solution into chlorine, hydrogen and sodium hydroxide.
What is chlorine used for?
Disinfectants, killing bacteria (in water supplies), household bleach, plastics, hydrochloric acid and insecticides.
What is hydrogen used for?
Ammonia, changes fats into oils for making margarine, for welding and cutting, and as a fuel in fuel cells.
