Chemistry - C2 Flashcards
Which theory is now widely accepted?
- the plate tectonic theory
What does evidence need to be for a theory to be accepted?
- repeatable
- agreed
What processes are rock recycled by?
- geological processes
What are rocks used as?
- building materials
Concrete isn’t very strong but what can it be reinforced with to make stronger?
- steel
What are metals extracted from?
- rocks
What do alloys contain?
- at least one metal but have different properties
What is copper extracted and purified by?
- extracted by reduction
- purified by electrolysis
What does iron rust in contact with?
- oxygen and water
What speeds up rusting?
- salt
What is aluminium and what are its characteristics?
- aluminium is a metal with a low density, which does not corrode because it has a protective oxide layer
Is the haber process a reversible or irreversible reaction and what does it make?
- reversible
- ammonia
What is ammonia used to make?
- nitrogen fertilisers
What is the neutralisation equation?
- acid + base –> salt + water
What can fertilisers cause?
- eutrophication
What do acids react with to make salt?
- metal oxides and hydroxides, and also metal carbonates
What is sodium chloride?
- it is an important raw material, obtained by mining it from the ground or by solution mining
What is electrolysis used to do?
- it is used to split sodium chloride solution into hydrogen, chlorine and sodium hydroxide
In electrolysis, where do they positive and negative ions go?
- the positive ions move to the cathode and the negative ions to the anode
What do plate movements cause?
- earthquakes
- volcanoes
What is thermal decomposition?
- it is a reaction where one substance breaks down on heating to give at least two new substances
What is reinforced concrete?
- it is a composite material which has steel rods or meshes running through it. Composites contain at least two materials that can still be distinguished
What are some advantages of recycling copper?
- it has a fairly low melting point so the energy cost to melt is low
- it reduced the need for mining, saving reserves and the environmental problems caused by mining
- it keeps the cost of copper down
What are some disadvantages and problems of recycling copper?
- the small amounts used in electrical equipment are difficult to separate
- valuable ‘pure’ copper scrap must not be mixed with less pure scrap, such as solder
- less copper is mined so there are fewer mining jobs
- the actual separating process may produce pollution
- a lot of copper is thrown away as it is difficult to persuade people to recycle it
