Chemistry IGCSE: Reactivity Series 2f
What four metals should you know which are less reactive than hydrogen from most to least reactive?
1. Copper 2. Silver 3. Gold 4. Platinum They are generally found native (uncombined in nature).
Write a balanced symbol equation, with state symbols, for the reaction of lithium with water.
2Li(s) + 2H₂O(l) -->2LiOH(aq) + H₂(g)
How can the position of a metal in the reactivity series be deduced using displacement reactions?
A more reactive metal will displace a less reactive metal from its compound. E.g. Mg(s) + CuO(s) -->MgO(s) + Cu(s) E.g. Mg(s) + CuCl₂(aq) -->MgCl₂(aq) + Cu(s)
What is a redox reaction?
A reaction in which both reduction and oxidation are taking place.
Displacement reaction
A reaction where the more reactive element displaces the less reactive one from a compound
What is a reducing agent?
A substance capable of reducing another substance. E.g. Mangesium is causing copper oxide to be reduced (lose oxygen) Mg(s) + CuO(s) -->MgO(s) + Cu(s)
What is an oxidising agent?
A substance that is capable of oxidising another substance. Something which provides oxygen for a compound. E.g. Copper being oxidised by oxygen. 2CuO + O₂ -->2CuO E.g. Magnesium being oxidised by copper oxide (Copper oxide is the oxidising agent). Mg(s) + CuO(s) -->MgO(s) + Cu(s)
Aluminium reacts with iron(III) oxide to form aluminium oxide plus iron. 2Al + Fe₂O₃ → Al₂O₃ + 2Fe a) Explain why this reaction occurs
Aluminium is more reactive than iron (and so will displace iron from its compounds)
Aluminium reacts with iron(III) oxide to form aluminium oxide plus iron. 2Al + Fe₂O₃ → Al₂O₃ + 2Fe a) What has been oxidised? What is the oxidising agent? a) What has been reduced? What is the reducing agent?
Aluminium reacts with iron(III) oxide to form aluminium oxide plus iron. 2Al + Fe2O3 → Al2O3 + 2Fe Aluminium has been oxidised by iron oxide iron oxide has been reduced by aluminium which is the reducing agent
Aluminium reacts with iron(III) oxide to form aluminium oxide plus iron. 2Al + Fe₂O₃ → Al₂O₃ + 2Fe Why can this be described as a displacement reaction?
Aluminium replaces iron in iron (III) oxide
Why can iron be extracted from iron oxide by heating with carbon? Why can't all metals be extracted with carbon?
Because carbon is more reactive than iron, thus can displace the iron in the iron oxide Because there are metals that are more reactive than carbon, meaning that they will not be displaced by it. E.g. Aluminium
How do you extract a metal from a metal oxide when the metal is less reactive than carbon?
By reducing the metal oxide using carbon. E.g. Copper oxide is reduced using carbon as a reducing agent. E.g. C + 2CuO -->CO₂ + 2Cu
Write a balanced symbol equation, with state symbols, for the reaction of calcium with water.
Ca(s) + 2H₂O(l) --> Ca(OH)₂(aq) + H₂(g) If you add enough calcium eventually no more calcium hydroxide will dissolve and the solution will go cloudy. Ca(s) + 2H₂O(l) --> Ca(OH)₂(s) + H₂(g)
What are the observable signs of reaction of calcium with water?
Calcium moves up and down in water, solution turns cloudy, calcium disappears. Bubbles are observed.
Thermite Reaction - A very useful displacement reaction used to produce iron for welding. What are the products? Fe₂O₃ + 2Al →
Fe₂O₃ + 2Al → Al₂O₃ + 2Fe
What is galvanised iron?
Galvanised iron is iron that is coated with a layer of zinc. To begin with, the coating will protect the iron. If the coating is damaged or scratched, the iron is still protected from rusting; zinc is more reactive than iron and so it reacts and corrodes instead of the iron.
Iron can be protected from rusting by coating it with zinc i) What is the name for this method of protection?
Galvanising
Which is more reactive group 1 or group 2 metals?
Group 1 metals are more reactive. Evidence would be how much more vigorous group 1 metals are with water
What is the chemical name for rust?
Hydrated iron (III) oxide
How is zinc used on ships?
If zinc blocks are attached to the hulls of ships, they will corrode instead of the hull. The zinc is called a sacrificial anode.
How does the reactivity change as you go down group 1 of the periodic table?
Increase in reactivity as you go down. Lithium is the least reactive group 1 metal. Evidence would be how much more vigorous group 1 metals further down the group are with water
What can speed up the rusting?
Increase in temperature Have salty water
What is a reducing agent?
It bring about reduction, and is itself oxidised E.g. Aluminium in the reaction below is a reducing agent. Aluminium + copper oxide -->aluminium oxide + copper
What is a oxidising agent?
It brings about oxidation, and is itself reduced. E.g. Copper oxide in the reaction below is a oxidising agent. Aluminium + copper oxide -->aluminium oxide + copper
Does copper react with dilute acids?
It does not react.
Is a displacement reaction endothermic or exothermic Exothermic reactions release heat to the surroundings resulting in a temperature rise. Endothermic reactions take heat from the surroundings resulting in a temperature decrease
It is exothermic.
On a separate piece of paper write down the reactivity series of the metals - you may wish to put hydrogen and carbon in but surround them brackets.
K, Na, Ca, Mg, Al, (C), Zn, Fe, (H), Cu, Ag, Au, Pt Potassium, Sodium, Calcium, Magnesium, Aluminium (carbon), Zinc, Iron, (hydrogen), Copper, Silver, Gold, Platinum
Write a word equation for the reaction between magnesium and hydrochloric acid. Hint: Magnesium is in group 2 of the periodic table and hydrochloric acid consists of equal amounts of hydrogen and chlorine
Magnesium + hydrochloric acid -->magnesium chloride + hydrogen
Metal + (cold) water forms what products?
Metal hydroxide + hydrogen
What are the observable signs of reaction of lithium (or sodium) with water?
Metal moves across surface of water and disappears. Fizzing observed.
Metal + steam forms what products?
Metal oxide + hydrogen
Metal + acid forms what products?
Metal salt + hydrogen
The reaction between metals farther apart in series will be (more/less) reactive
More
What is oxidation?
Oxidation is the addition of oxygen to a compound. (There is an additional definition which will be covered elsewhere.) E.g. Copper being oxidised. 2Cu + O₂ -->2CuO
Why does aluminium seems to be less reactive then it is according to reactions with water, steam and acid?
Protective layer of aluminium oxide
How can the reactivity series for the metals be worked out?
React metals with water, steam, acids or carry out displacement reactions with compounds of other metals
Iron can be prevented from rusting by attaching a piece of a more reactive metal. What is this method of protection called?
Sacrificial protection
What are the observable signs of reaction of magnesium with steam?
Shiny solid becomes a white solid.
Why is there no temperature rise when silver is added to iron(II) sulfate solution?
Silver is less reactive than iron (and so will not displace iron from its compounds). Displacement reactions release heat into the surroundings (an exothermic reaction) and will cause a temperature rise
Write an equation for the reaction between magnesium and hydrochloric acid. State symbols are optional Hint: Magnesium is in group 2 of the periodic table and hydrochloric acid consists of equal amounts of hydrogen and chlorine
Symbol equation:Mg(s) + 2HCl(aq) --> MgCl₂(aq) + H₂(aq)
How are metals arranged into the reactivity series?
The Reactivity series is based on the reactions of the metals and their compounds.
How do you know from the reactions with cold water that potassium is more reactive than lithium?
The reaction is more vigorous with potassium than with lithium - faster rate of bubbling. (FYI Enough heat generated to cause hydrogen to catch light and burn.)
How do calcium, magnesium, zinc and iron react with dilute acids? What would you observe?
They react with decreasing vigour as the series is descended, to form the metal salt and hydrogen.
Predict how potassium, sodium, and lithium react with dilute acids.
They would react very vigorously to form metal salt and hydrogen. The reaction may be too vigorous and thus not carried out.
How can rusting be prevented?
This can be done in a number of ways by coating the iron with grease, oil, paint, plastic, or a less reactive metal.
What conditions must be present for rusting of iron to occur?
Water and oxygen must both be present for rusting to occur.
What is reduction?
When the oxygen is removed from a compound (There is an additional definition which will be covered elsewhere) E.g. Copper oxide is being reduced (losing oxygen) by magnesium Mg(s) + CuO(s) -->MgO(s) + Cu(s)
What would you observe when magnesium reacts with a dilute acid?
You would see the metal disappear and bubbling being formed (due to hydrogen gas being formed under a liquid)
How does galvanising protection iron?
Zinc corrodes to form a thin zinc oxide layer that acts as a barrier, if the zinc coating is scratched, it continues to provide protection via sacrificial protection.
How does zinc protect iron?
Zinc is above iron in the reactivity series, so zinc reacts more readily than iron.
Zinc reacts with iron(II) sulfate to form zinc sulfate plus iron Zn(s) + FeSO₄(aq) → ZnSO₄(aq) + Fe(s) a) Explain why this reaction occurs
Zinc is more reactive than iron (and so will displace iron from its compounds)
Suggest a metal which could be used for this
Zn/Mg/Zinc/Magnesium