C3- Chemicals In Our Lives Flashcards
How is sedimentary rock formed?
Limestone
Limestone - consist of mostly calcium carbonate
Erosion is the natural weathering of large pieces of rock by the rain and wind which creates tiny particles of sediment which are washed away and end up at the bottom of seas or lakes
Over millions of years the sediment is buried under more layers and the weight pressing down squeezes out the water
Fluids flow through the pores in the sediment deposit natural mineral cement that hold the sediment particles together to form rock
How is coal made?
Another type of sedimentary rock
Black in colour and formed over millions of years by the fossilisation of layers of plant matter.
Consists of mainly carbon
Hard coal is formed when high pressure an temperatures, can happen during mountain building process
Salt is left behind by evaporation, how?
Salt is extracted from underground deposits
Underground deposits were formed when ancient seas containing dissolved salt evaporated. Salt left behind was buried and compresses by other layers of sediment over millions of years.
How does salt mining happen?
Rock salt is drilled, blasted and dig out and brought to the surface using machinery.
Most rock salt obtained through this type of mining is used in roads to stop ice forming.
The salt can also be separated out and used to enhance the flavour of food or for making chemicals
How does solution mining take place instead of salt mining
Water is injected into the salt deposits though the outer pipe.
Which dissolves the salt to make saltwater solution called brine.
Pressure forces the bribe up to the surface through the inner pipe
The brine is then stored in wells above the surface and pumped to a refining plant when needed
Impurities are removed from the brim in the refining plant and its then pumped into containers. The brine is then boiled to make the water evaporate, leaving the salt behind.
> most table salt and salt used for chemical production is produced in this way
Negatives of both way to produce salt:
- collapse into holes ( SUBSIDENCE)
- ^it is reduce by leaving well supported caverns in mines (pillars of rocks)
- mining needs a lot Of energy which comes from burning fossil fuels causing pollution
Salt obtained from the sea:
In hot countries it is obtained by evaporating seawater
Water flows in special built shallow pools and is left to evaporate in the sun, leaving salt behind.
Process is then repeated several times and salt is then collected
Method produced the purest salt - can be nearly 100% sodium chloride
Salt in food production:
Refined salt is added to processed foods to enhance FLAVOUR.
Used as a PRESERVATIVE.
Kills the bacteria cells when the meat has dried and absorbed the salt and the meat is preserved
Health issues of the use of salt
- eating too much cause high blood pressure, leads to heart attacks and strokes
- increase chances of stomach cancer, osteoporosis and renal failure due to too much consumption
Government ways for guidelines for salt intake
- GDA ( Guideline Daily Amounts)
- risk assessments for chemicals in the food to make sure they’re safe and then advise the public about how good affects their health
Why is salt an important source of chemicals?
- salt ( sodium chloride) is important for the chemicals industry
- they elecyruse the salt solution (brine) which involves passing an electric current through it
- electrolysis cause chemical change - splits the solution into HYDROGEN, CHLORINE, SODIUM HYDROXIDE
Uses for chlorine
- disinfectants
- killing bacteria
- household bleaches
- plastics (PVC)
- hydrochloric acid
- insecticides
Uses for hydrogen
Used to make ammonia
Used to change oils in fat for making margarine
Use as a fuel in fuel cells, for welding and metal cutting
Uses of sodium hydroxide
Very strong alkali and is used widely in the chemical industry
Soap Ceramics Organic chemicals Paper pulp Oven cleaner Household bleach
Environmental impacts of large scale electrolysis
Needs lots of energy
Burns fossil fuels - realises pollutants such as carbon dioxide
Mercury is toxic - contamination caused fisheries to close
Asbestos- is an toxic chemical an can cause lung cancer
