C4 - Chemical Calculations
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What is a mole
A number of particles (equal avogardo’s number)
What is the reactivity series?
A list of elements ordered by their reactivity
How can metals be placed in order of their reactivity?
Add the metals to water or acid and see which ones react the most vigorously
What is the name for a reaction where oxygen is removed from a compound?
Reduction
Why is gold found in the Earth’s crust as the metal itself?
It is unreactive
What process is used to extract metals less reactive than carbon?
Reduction with carbon
What process is used to extract metals more reactive than carbon?
Electrolysis
What is an ore?
A material containing enough metal in it for it to be economically worthwhile to extract the metal
Name two new ways of extracting copper from low-grade ores
Phytomining and bioleaching
What is a low grade ore?
Rock with only a small amount of metal compound in it
How is phytomining carried out
Phytomining uses plants to absorb metal compounds. The plants are harvested and then burned to produce ash that contains metal compounds
How is bioleaching carried out?
Bacteria are used to produce a leachate solution that contains metal compounds. The metal compounds can be processed to obtain the metal. Displacement using scrap iron or by electrolysis.
How can copper be produced from the products of phytomining and bioleaching?
Electrolysis or displacement with scrap iron
What is a displacement reaction?
A reaction in which a more reactive element takes the place of a less reactive element in one of its compounds or in solution
Define oxidation in the context of loss or gain of electrons
Oxidation is the loss of electrons
Define reduction in the context of loss or gain of electrons
Reduction is the gain of electrons
What is corrosion?
The destruction of materials by chemical reactions with substances in the environment
What is necessary for rusting to occur
Water and air
How can rusting be prevented?
By use of a barrier coating or sacrificial protection
Give three examples of barrier coating
Greasing, painting, electroplating
How does sacrificial protection work?
A more reactive metal is corroded rather than the base metal
Define acids in terms of pH
A substance with a pH less than 7
Define acids in terms of ions
A substance which releases H+ ions in solution
State the three common acids and give their formulae
Hydrochloric acid, HCl (aq), Sulfuric acid, H2SO4 (aq), Nitric acid, HNO3 (aq)