Oxidation, reduction, displacement reactions Flashcards
(20 cards)
Oxidation
-gain of oxygen/loss of electrons by a substance during a chemical reaction
Reduction
-loss of oxygen/gain of electrons by a substance during a chemical reaction
If an iron nail is left in damp air for a while…
…it will rust (iron oxide).
Why is pure iron rarely found on Earth?
-it oxidises really easily in air or moisture
-forms iron oxide
Why are most metals found in the Earth’s crust as ores rather than in their pure metal form?
-a lot of metals, such as iron or calcium, oxidise easily in air/moisture
-so they form metal oxides or carbonates
Ore
-rock that contains enough of a metal to make it worth extracting the metal for profit
In terms of oxidation, the metals higher in a series oxidise much more easily/ harder than metals lower in a series
-easily
If a metal is higher in a series, will it form oxides or corrode much faster?
-yes
Metals at the bottom of the reactivity series are often found in their ? ? as they are so ? that they are ? to oxidation
-pure form
-unreactive
-resistant
If a metal oxide is above carbon in a reactivity series, can it be reduced by it?
-no
-carbon can only take away oxygen from metals less reactive than itself
How do we reduce a metal (above carbon in the reactivity series) from its oxide?
-electrolysis
Why can we use carbon to get pure iron from its ore?
-carbon is higher in the reactivity series than iron
-so it can reduce its ore by removing the oxygen
Why cant we react magnesium with magnesium sulfate?
-a metal cannot displace itself from a solution of one of its salts
-so the reaction cannot be done
Where are most ores found in?
-the Earth’s crust
So when doing a displacement/redox reaction between copper sulphate with magnesium..
..you oxidise magnesium, as its atoms lose two electrons and form positive ions.
…you reduce the copper ions by making them gain two electrons, making them neutral
-balanced ionic equation (as they both gain/lose same number of electrons) and can be split into 2 half equations
Example of oxidation reaction
-magnesium burning rapidly in air
magnesium + oxygen -> magnesium oxide
Two examples of redox reactions:
-displacement
-electrolysis
Mg(s) + Cu2+(aq) → Mg2+(aq) + Cu(s)
Ionic or half equation?
Ionic equation
Mg(s) → Mg2+(aq) + 2e-
Ionic or half equation?
Half equation
Difference between ionic and half equations?
-ionic equations show all the ions that are changing but miss out on any “spectator” ions that don’t change
-half equation shows one side of a redox reaction, either the reduction side or the oxidation side
