C1 Atoms And Products From Rocks and oil. Flashcards
What does the top number on a periodic table symbol mean?
The mass number. The total number of protons and neutrons.
What is an element?
A thing made of only one type of atom.
What does the bottom number on a periodic table symbol mean?
It is the atomic number. This is the number of protons which also tells you the number of electrons.
How do you find the number of neutrons of an atom?
Subtract the atomic number from the mass number.
Why are ions attracted to each other?
They from an ionic bond as they are of opposite charges and so are attracted to each other.
What is a compound that forms from two non-metals?
A covalent bond.
What is limestone?
Calcium carbonate. CaCO”3”
What happens when calcium carbonate thermal decomposes?
Calcium carbonate = calcium oxide + carbon dioxide.
CaCO”3”. CaO. CO”2”
What happens when magnesium, copper, zinc or sodium carbonates are heated?
They will thermally decompose in the same way calcium will.
What happens when calcium carbonate is reacted with acid?
A salt, CO2 and water will be made.
Calcium carbonate+ sulphuric acid=calcium sulphate + CO2+H2O
CaCO”3”. H”2”SO”4”. CaSO”4”
The salt created will depend on the acid used.
What happens when water is added to calcium oxide?
CaO + H”2”O = Ca(OH)”2”
Calcium hydroxide will be made.
What can calcium hydroxide be used for?
It is an alkali so it can be used to neutralise acidic soil in fields. Powdered limestone can be used for this as well but the hydroxide works faster.
Also, if it is mixed with water you get limewater which can detect CO2
What happens when calcium hydroxide is mixed with carbon dioxide?
Calcium hydroxide + CO”2” = calcium carbonate + water.
Ca(OH)”2”. CaCO”3”. H”2”O
How can limestone be used in construction?
Powered limestone is heated in akin with powdered clay to make cement.
Cement can be mixed with sand and water to make mortar. Mortar is the stuff used to stick bricks together. Calcium hydroxide can also be used.
Or cement can be mixed with sand and aggregate to make concrete.
What is a problem with quarrying limestone?
It makes huge ugly holes which alter the landscape.
Quarrying processes make lots of noise and dust in quiet scenic areas.
It destroys the habitats of animals and birds.
The limestone needs to be transported away. This causes noise and pollution.
Waste materials produce un slightly tips.
How does using limestone cause pollution?
Cement factories make a lot of dust which can cause breathing problems.
Energy is needed to produce cement and quicklime. The energy will come from burning fossil fuels.
What are the positives of mining limestone?
It can be used to build things.
Limestone can be used to neutralise acidic soil or acidic rivers.
It it neutralise sulphur dioxide which is produced by power stations.
Quarrying provides jobs and adds money to the local economy.
Landscaping and restoration of the area is normally required as part of the planning persission.
What are the pros of using limestone?
It is widely available and cheaper than granite or marble. It is easy to cut.
It looks attractive and can be more hard wearing than marble.
Concrete can be poured into moulds to make blocks. It is quick and cheap but very un attractive.
It’s fire resistant, doesn’t rot and can’t be gnawed by animals.
Concrete doesn’t corrode. It has a very low tensile strength which can be improved by steel bars.
What is an ore?
A rock with enough of an element in it for it be economically viable to extract it.
How can the economics of metal extraction change?
If the market price drops, it might not be worth extracting it.
If the price goes up, it might be worth extracting more of it.
As technology improves it can make extracting metal cheaper.
How can a metal be extracted from an ore?
It can be done chemically by reduction or by electrolysis.
Some ores may have to be concentrated before extraction.
Electrolysis can be used to purify the extracted metal.
How can some metals be extracted by reduction with carbon?
Oxygen will be removed from the ore.
2Fe”2”O”3” + 3C = 4Fe + 3CO”2”
The Metals will have to be less reactive than carbon for this to work.
Why is electrolysis used to extract certain metals?
They are more reactive than carbon so can’r be displaced.
Why is copper purified with electrolysis?
It is extracted with reduction with carbon when it is smelted.
However this isn’t very pure.
It is electrolysed so as to purify it so it is a better conductor.
What is electrolysis?
The breaking down of substances using electricity.
Describe electrolysis.
It requires a liquid to conduct the electricity, called the electrolyte.
They are often metal salt solutions made from the ore or molten metal oxides.
The electrolyte has free ions which means it conducts electricity.
Electrons are taken away by the anode and given by the cathode. As ions gain or lose electrons they become atoms or molecules and are released.
How is copper extracted by electrolysis?
Electrons are pulled off copper atoms at the anode causing them to go into the solution as Cu 2+ ions.
Cu2+ ions near the cathode gain electrons and turn back into the copper atoms.
The impurities are dropped at the anode as sludge, whilst pure copper atoms bond to the cathode.
The anode is a lump of impure copper which gets dissolved.
The cathode starts as a thin piece of pure copper which gets bigger.
What happens if reactive metals are out into a solution of a dissolved metal compound?
Give an example.
The more reactive metal will replace the less reactive metal in the compound.
Scrap iron is put in a copper sulphate. Copper metal and iron sulphate will be produced.
How can copper be extracted from low grade ores?
What are the pros and cons of these methords?
Bio leaching and phytomining. They damage the environment less but they are slow.
How does bio leaching work?
Bacteria separates copper from copper sulphide. The bacteria get energy from the bond between copper and sulphur, separating out the copper from the ore in the process. The leachate (solution produces) contains more copper which can be extracted.
How does phytomining work?
Plants are grown in copper rich soil.
The copper gets built up in the leafs. The plants can be harvested dried as burned in a furnace.
The copper can be collected from the ash.
Why is recycling metal important?
Making and extracting metals takes energy which comes from fossil fuels.
Fossil fuels are running out so its important to conserve them. Also using them causes global dimming and global warming. Recycling metal uses only 15% of the energy used to mine more.
It is cheaper.
There is a finite amount of metal in the Earth.
Recycling means less goes into land fill.
What are the properties of copper?
It is a good conductor of electricity so it is good for electrical wires. It’s hard and strong but can be bent. It doesn’t react with water.
Used in plumbing.
