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Displacement reactions

17/05/2016 ©cgrahamphysics.com 2016

Starter: match them up


Elements for speed dating

Hydrogen

Oxygen

Carbon

Sodium Magnesium

Chlorine

Helium Fluorine Potassium Calcium

Sulphur

Bromine Iron copper Zinc


Speed dating • Interactive periodic table

• You will draw an element. You have 4 minutes to fill out your dating sheet with information

• Metals will stay seated. Non Metals will move around and try to catch a “date”

• Write down your combined name

• Decide by the end of the class if your combination is possible


http://www.ptable.com/

Aim • Be able to use displacement reactions to

deduce the position of a metal within the

reactivity series

Key words

• Reactivity

• Displacement reaction 치환반응

• Reactivity series 연쇄 반응


The big picture

Can you predict when a displacement reaction will occur?

Have you ever wondered 17/05/2016 ©cgrahamphysics.com 2016

Recap: the reactivity series

potassium sodium lithium calcium

magnesium aluminium

zinc iron

copper silver gold

most reactive

least reactive

K Na Li Ca Mg Al Zn Fe Cu Ag Au


9F Feeling a bit displaced?

A displacement reaction happens

when one metal replaces another

one in a compound.

Magnesium is more reactive

than copper.

magnesium + copper sulphate magnesium sulphate

+ copper

Magnesium displaces copper from copper sulphate solution, e.g.

Displacement Reactions


Cartoon displacement

Mr Sulphate Miss Iron

Iron sulphate

Miss Zinc +

+ Zinc

Miss Zinc

Zinc Sulphate + Iron

Mr Sulphate Miss Iron


9F A model for displacement reactions



• If a more reactive metal is placed into one of these metal solutions it will react and displace the other metal

• For example the reaction between copper sulphate and magnesium

Copper sulphate (blue)

Magnesium Magnesium Sulphate (clear)

Copper


The copper in the copper

sulphate is turning into

red copper metal.


• Reaction between copper sulphate and magnesium.

• Why does the blue copper sulphate colour gradually disappear?


Mg

Magnesium

SO4 Cu

Copper sulphate

The magnesium

DISPLACES the copper

from copper sulphate

SO4 Mg

Magnesium sulphate

Cu

Copper

Magnesium + copper sulphate magnesium sulphate + copper

Displacement reactions


Your Experiment

• You have been given the following:

copper copper sulfate solution

iron iron sulfate solution

magnesium magnesium sulfate solution silver silver nitrate solution

• Organise a series of experiments to determine the order of reactivity for all 4 metals


Table

Magnesium Iron Copper Silver

Magnesium sulfate solution

Iron sulfate solution

Copper sulfate solution

Silver nitrate solution


1) When steel wool is placed in copper sulphate solution, the wool turns into a pink powder and the solution goes from blue to yellow in colour. Steel is a form of iron. Explain this observation

2) Mercury is an unreactive metal, below copper in the reactivity series. It is highly toxic. Jo placed some zinc metal into a beaker of mercury chloride solution. She noticed small silver beads appearing at the bottom of the beaker. Explain this observation using a word/symbol equation.

3) Explain how you could extract silver metal from a solution of silver nitrate using the idea of metal displacement reactions.

4) Paul was given some tin metal, tin chloride solution, lead metal and lead nitrate solution. Describe how Paul would be able to work out whether tin or lead is the more reactive metal.

Answer these questions in your book


copper + magnesium sulphate

copper sulphate

+ magnesium

zinc + magnesium sulphate

zinc sulphate + magnesium

iron + magnesium sulphate

iron sulphate + magnesium

Magnesium


No reaction magnesium sulphate

+ Zinc

iron + zinc sulphate iron sulphate + Zinc

copper + zinc sulphate copper sulphate

+ Zinc

Zinc



+ copper

No reaction zinc sulphate + copper

No reaction copper sulphate

+ copper

Copper



+ iron

No reaction zinc sulphate + iron

copper + iron sulphate copper sulphate

+ iron

Iron


Plenary

Hydrogen

Oxygen

Carbon

Sodium Magnesium

Chlorine

Helium Fluorine Potassium Calcium

Sulphur

Bromine Iron copper Zinc

17/05/2016

• Look back at the combinations you formed at the beginning • Which element can steal the non metal from your compound?

©cgrahamphysics.com 2016

Plenary: Questions

Look at this table and answer all questions on the sheet

Mg Fe Zn Mg

ZnSO4 CuSO4 FeSO4 CuSO4

silvercoloured

darkgrey

lightgrey

silvercoloured

colour ofmetal at start

colour ofsolution at

start

appearenceof metal at

end

colour ofsolution at

end

colourless

light grey

colourless

pale blue

brown

palegreen

pale green

colourless

pale blue

diagram ofexperiment


Key words • Reactivity - the tendency of a substance to undergo a chemical reaction, either by itself or with other materials, and to release energy.

• Displacement reaction – a reaction in which a more reactive element displaces a less reactive element from its compound.

• Reactivity series – an analytical progression of a series of metals, arranged by their "reactivity" from highest to lowest.


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