Flashcards in C3: UNFINISHED Deck (70):
Why do geologist study rocks?
To see how Earths rocks surface has changed
What do geologist look at?
-They look at how rocks form
-How rocks change
-And when changes happen
What was the super-continent known as?
Originally were was Britain located?
Near the equator
As volcanic lava solidifies, what rock is formed?
The Earth's magnetic field...
changes over time.
How can magnetic patterns help geologist find out the Earth's movement?
The rocks are aligned with the Earth's magnetic field so geologist track the slow movement of continents.
What are the three most important raw materials?
Coal,Salt and Limestone
What started 200 years ago in the north-west of England?
Where was there large deposits of coal?
Cheshire had large deposited of ...
Where was there large deposits of Limestone?
Name 3 uses of Salt
1. In the food Industry
2. As a source of chemicals
3. To treat icy roads
How can salt be obtained?
1. Evaporation pools
2. mining underground salt deposits
Why is salt put on icy roads?
-Mixed with sand it gives the ground grip
-the salt lowers the freezing point allowing ice to melt
Salt extraction from sea water...
is only economical in hot climates
What method obtains purer salt?
What is a risk of mining rock salt and solution mining?
Why can some salt not be mined?
Half the rock salt is left for support: so subsidence don't happen
What do you do if you need more salt?
You import it
What is a risk of solution mining?
Water may leach out and contaminate water supplies
What is a risk of Evaporation pools?
It takes up large areas and spreads salt into the local environment, damaging habitats.
Why is salt used in the food industry?
for flavouring and as a preservative.
How does salt act as a preservative?
Higher levels of salt prevents bacteria growth
High blood pressure, heart failure and stroke are results of WHAT?
Too much salt intake
Why is salt a hazard?
Because it poses a risk to health
Who is in charge for carrying out a risk assessment for chemicals in food and advising the public about how food affects health?
The government Department of Health (DH) and the Department of the Environment, Food and Rural Affairs (Defra)
Alkalis make What change colour?
Alkalis neutralise acids to make salts, what is this process called?
Acid + Alkali =
salt + water
What are alkalis used for :
1. Neutralising acid soil
2. Making soap
3. Making glass
How was soap made in the past?
Using a mixture of potash (burnt wood) and animal fat , which is boiled
What was the first alkali manufactured and how?
Calcium oxide (lime) and by heating limestone (calcium carbonate) in a lime line using coal as fuel
Name 4 main acids
2. Nitric acid
3. Sulfuric acid
4. Phosphoric acid
In 1787 , what Frenchman discovered how to manufacture an alkali?
What was the Leblanc process?
Reacting salt and limestone in heat to form sodium carbonate
What was the problem with the Leblanc process?
It released lots of Hydrogen chloride (an acidic, harmful gas) and solid waste called galligu (which in turn released hydrogen sulfide a toxic gas)
What did the better process do to the waste hydrogen chloride?
It made it useful by
-using chlorine to bleach textiles prior to dying
-and hydrochloric acid, was used as a starting material for other chemicals
A solution with a pH greater than 7 is known as a what?
What colours does alkalis turn indicators
Blue or violet
Give 2 examples of a metal hydroxide
NaOH and Ca(OH)2
Alkalis are soluble...
Metal hydroxides and Metal carbonates
When metal hydroxides and metal carbonates are insoluble what are they called?
Hydroxide + acid =
salt + water
carbonate + acid =
salt + water + carbon dioxide gas
Why did people die from drinking water in the 19th century?
Because they got water-borne diseases like cholera and typhoid
What is now added to drinking water?
What is the process of added chlorine to drinking water?
Who has no choice about chlorination?
Those who use the main water supply.
Chlorine can react with organic materials in water supplies forming WHAT?
Disinfectant by-products (DBPs)
Why does the government carry on chlorination anyway?
Because the benefits outweigh the risks.
What is Electrolysis?
Breaking up a compound using an electric current
Name the products when you electrolyse brine
-Sodium hydroxide solution
The anode is the ...
The cathode is the...
Why is electrolysis expensive?
Because it requires large amounts of electricity
Name one method to electrolyse brine continuously
The membrane cell
Where does chlorine form during electrolysis?
At the at the anode
What forms at the cathode?
What can chlorine be used for?
In plastics like PVC
What can hydrogen be used for?
In margarine and as rocket fuel
What can sodium hydroxide be used for?
In paper recycling and refining aluminium
What are the risks of chlorine?
-Chlorine in products is linked to ozone depletion
-Plastics made using chlorine are non-biodegradable
What is a used to find out how dangerous substances are?
A risk assessment
What four things do you need to know to assess the level of risk of a chemical?
-how much is needed to cause harm
-how much will be used
-the chance of it escaping into the environment
-who or what it may effect
What does PVC contain?
Carbon, Hydrogen and Chlorine
What are added to PVC to make them softer?
What are plasticised PVC used for?
Seat covers, clothing and cover electrical wires
What did USA and Europe ban?
Plasticised PVC in toys