The Reactivity Series Flashcards
List the reactivity series
Potassium K+ Sodium Na+ (Lithium) Calcium Ca2+ Magnesium Mg2+ Aluminium Al 3+ Zinc Zn2+ Iron Fe2+ and Fe 3+ (rusts slowly in moist air) Tin Sn2+ Lead Pb2+ Copper Cu2+ Silver Ag+ Gold Au2+
Why does aluminium not readily react?
It has a passive oxide layer
What happens as you go up the reactivity series?
The reactivity of each metal increases, whilst the reactivity of the metal ions decreases
Temperature can change reactivity
Which metals slowly tarnish in cold air?
Potassium Sodium Calcium Magnesium Aluminium Zinc Iron Tin Lead Copper and silver
Which metals burn in air to form oxides and the colour of their oxides is white?
Potassium Sodium Calcium Magnesium Aluminium Zinc Iron (has brown oxide though)
What metals form oxides without burning?
Tin (black oxide)
Lead (yellow oxide)
Copper (black oxide)
What metals have an explosive reaction with dilute acid?
Potassium
Sodium
Calcium
How does magnesium, aluminium, zinc, iron and tin react with dilute acid?
They all react with dilute HCL and H2SO4 to form hydrogen and the metal chloride/sulphate
How does lead, copper, silver and gold react with dilute acid?
They do not react with HCL or H2SO4 but may be oxidised by HNO3
How does potassium react with cold water?
Explodes and reacts to give hydrogen and forms alkaline hydroxide
How does sodium react with cold water?
Fizzes and reacts to give hydrogen and forms alkaline hydroxide
How does calcium react with cold water?
Bubbles and reacts to give hydrogen and forms alkaline hydroxide
How does magnesium react with cold water?
Very slowly
Which elements do not react with cold water?
Aluminium Zinc Iron Tin Lead Copper (hence why it can be used for both hot and cold pipes) Silver Gold
What happens when magnesium, aluminium, zinc and iron are heated in steam?
They all react to give hydrogen and form metal oxides when heated
Which metals do not react with steam?
Tin Lead Copper Silver Gold
Describe potassium when it reacts with water
catches fire (ignites hydrogen which burns with a lilac flame), fizzes, lilac flame and disappears
Describe sodium when it reacts with water
floats, fizzes, melts and moves around
Describe lithium when it reacts with water
moves around, fizzes, floats (does NOT melt)
Describe metal hydroxides?
-Soluble in water and
Describe calcium when it reacts with water
- Reacts gently, grey calcium granules sink to the bottom but are carried back to the surface again as bubbles of hydrogen are formed around them
- The mixture becomes warm as heat is produced
- Calcium hydroxide is not very soluble but some of it dissolves to give a colourless solution but most of it is left as a white, insoluble solid
Describe magnesium when it reacts with water
- Almost no reaction, few bubbles of hydrogen form on it if hydrogen is very clean, but the reaction soon stops again
- This is because the magnesium soon becomes coated with insoluble magnesium hydroxide, which prevents water from coming into contact with the magnesium
Why do more metals react with steam?
- In steam, particles have more energy and so react faster and easier
- Hydrogen and oxides are formed because the H2O in steam makes the metal hydroxide split into metal oxide + hydrogen
What is an exothermic reaction?
A reaction which gives out heat energy (temperature rise)
What is an endothermic reaction?
A reaction that takes in heat energy (temperature falls)
What is an example of displacement reaction 2?
- Iron reacts with copper sulphate
- Forms iron sulphate and copper
- Copper sulphate will go from blue to pale green
- Iron will go from grey to brown
- CuSO4 + Fe –> FeSO4 +Cu
- If you put a piece of silver metal into a solution of copper sulphate, nothing happens, since the more reactive metal (copper) is already in the salt
What is an example of displacement reaction 1?
- Aluminium reacts with iron oxide
- Iron displaced from iron oxide by the more reactive aluminium
- Forms aluminium oxide and iron
- This is a thermite reaction: used for welding railway lines
- Fe2O3 + 2Al –> Al2O3 + 2Fe
What happens with hydrogen in displacement reactions?
- Hydrogen will reduce hot oxides of less reactive metals
- Hydrogen has a varying place because these reactions depend on temperature (which can change with reactivity)
What happens with carbon in displacement reactions?
-Carbon will reduce oxides low in reactivity
-This is useful for extracting metals from ores and carbon cheaply reduces oxygen from oxide leaving metal
-Reactive metals (e.g. magnesium) can reduce carbon dioxide
(Placed above Iron as does not EASILY reduce metal oxides higher up)
What needs to be present for iron to rust and form iron oxide?
- Water and oxygen (from the air) must be present
- Fe2O3 dark red rust
- Salt is a catalyst to the reaction (coast salt in air)
- The chemical reaction that takes place when iron corrodes is oxidation as the iron gains oxygen and becomes iron (III) oxide
- Water then becomes loosely bonded to the iron (II) oxide and the result is hydrated iron (II) oxide, which we call rust
- Iron + oxygen + water –> hydrated iron (III) oxide (rust)
What are the Barrier Methods for rusting?
- Paint/oil/grease/plastic can be used to cover oxygen to prevent oxygen and water getting to it
1. Paint and coating with plastic ideal for big and small structures alike, can be decorative too
2. Oiling and greasing has to be used when moving parts are involved, like on bike chains
What are the Sacrificial Methods for rusting?
- Using a more reactive metal rather than iron so that the oxygen and water will react with the sacrificial meta; instead of with the iron
- Galvanising iron covering it with a zinc layer (coating of zinc sprayed onto the object)
- Large lumps / big blocks of magnesium or zinc bolted to iron, used on ships’ hulls or on underground iron pipes / to pipes or boat keels to also react instead of iron
- Zinc is cheaper than aluminium or tin and the others are too reactive
Why does a more reactive metal displace a less reactive metal?
- Example 1:
1. More reactive metals react more strongly that less reactive metals
2. This means that a more reactive metal will displace a less reactive metal from its oxide because it will bond more strongly to the oxygen - Example 2:
1. Metal compounds like copper sulphate, zinc chloride and sodium chloride are metal salts
2. If you put a reactive metal into a solution of a less reactive metal salt the reactive metal will replace the less reactive metal in the salt
How would you deduce the position of a metal within the reactivity series using displacement reactions between metals and their oxides and between metals and their salts in aqueous solutions?
- Given a lump of a mystery metal and you could try reacting it with different metal oxides and salts
- If it reacted with copper oxide you would know it was higher in the series than copper
- If it didn’t react with magnesium sulphate you would know it was lower than magnesium in the reactivity series
