Unit 4 chemical changes
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What is the reactivity series?
A list of metals ordered by their reactivity
How can the order of reactivity for specific metals be found?
Add the metals to water or acid and see which ones react the most (by how much fizzing there is)
What is the name for a reaction where oxygen is added to form a compound?
Oxidation
What is the name for a reaction where oxygen is removed from a compound?
Reduction
Which metals do not react with acids?
Copper, silver, gold as they are less reactive than hydrogen
Explain why zinc can be extracted from zinc oxide with carbon but magnesium cannot be extracted from magnesium oxide with carbon
Magnesium is more reactive than carbon, Zinc is less reactive than carbon, Carbon can therefore remove oxygen from zinc oxide but not magnesium oxide
What is the order of the reactivity series from most reactive to least reactive?
Potassium Sodium Lithium Calcium Magnesium Aluminium Carbon Zinc Iron Hydrogen Copper Silver Gold
Explain why silver can be found pure in the Earth’s crust
It is very unreactive
What process is used to extract metals less reactive than carbon?
Reduction with carbon
Which metals are extracted by reduction with carbon?
Iron, Zinc and Copper
What process is used to extract metals more reactive than carbon?
Electrolysis
Define an ore
A rock containing enough metal in it for it to be economically worthwhile to extract the metal.
Define a displacement reaction
A reaction in which a more reactive element takes the place of a less reactive element
Define oxidation in terms of electrons
Oxidation is the loss of electrons
Define reduction in terms of electrons
Reduction is the gain of electrons
Which of the substances below has been oxidized and which has been reduced? Al³⁺ + Fe → Fe³⁺ + Al
Aluminium has been reduced and iron has been oxidised
Show two half equations for the reaction below: Al³⁺ + Fe → Fe³⁺ + Al
Al³⁺ + 3e⁻ → Al Fe → Fe³⁺ + 3e-
Define acid in terms of pH
A substance with a pH of less than 7
Define acids in terms of ions
A substance which releases H⁺ ions in solution
What does (aq) stand for?
Aqueous: when something is dissolved in water
State the three common acids and give their formulae
Hydrochloric acid, HCl, Sulphuric acid, H₂SO₄, Nitric acid, HNO₃
What is a neutral solution?
A solution with a pH of 7. Water is an example.
How do you measure pH?
With an indicator or pH probe
What is a base?
A metal oxide, hydroxide or carbonate, they react with acids.