Displacement reactions

WALT – Produce solutions using displacement reactionsWILF – ALL : Observe reactions between halogen compoundsMOST :Describe the displacement reaction processSome : Explain how displacement occurs using knowledge of halogen reactivity

Starter

• Name all the halogens IN ORDER!

• Which are the most/ least reactive?

• What properties can you remember about each of them?

3 people on a Saturday night out .

• Flo is a Fiat panda, Chloe a Bugatti Veyron• Tom drive the Panda and is looking for a new

car.

Flo Chloe

• Which car is likely to end up with Tom. • Tom has taken Chloe to the car shop, • Is Flo is likely to be able to ‘steal’ Tom from Chloe? • If Tom had gone with Flo, would Chloe have been

able to steal Tom?

Flo Chloe

Iron is able to ‘steal’ the sulphate from copper because it is more reactive

• You are going to carry out some displacement reactions to decide which metal is more reactive.

• Record your observations and fill in the answers below.

• Remember – In a displacement reaction, the more reactive metal displaces the less reactive metal from its compound.

• You are going to carry out some displacement reactions to decide which metal is more reactive. You are going to use ‘turnings’, which are small, curved pieces of metal.

• Your teacher will show you what to do. • Record your observations and fill in the answers

below.• Remember – In a displacement reaction, the more

reactive metal displaces the less reactive metal from its compound.

1. Which is the more reactive metal, zinc or copper?2. Complete this word equation: 3. zinc + copper sulphate → +

4. Which is the more reactive metal, magnesium or copper?

5. Complete this word equation: magnesium + copper sulphate → +

6. Which is the more reactive metal, zinc or magnesium?

7. Complete this word equation: magnesium + zinc sulphate → +

Thermit Reaction

• aluminium + iron(III) oxide ==> iron + aluminium oxide

• 2Al(s) + Fe2O3(s) ==> Al2O3(s) + 2Fe(s)

• http://www.youtube.com/watch?v=EpOJE-mkWmw• http

://www.youtube.com/watch?v=SjU5ixlyZtw&feature=related

• http://www.youtube.com/watch?v=7MKnrhs9ock&feature=related

• http://www.youtube.com/watch?v=PPAYZMzGMwQ&feature=related

Diplacement reactions

• alkali metals have different reactivities

• A more reactive element will ‘steal’ part of a compound from a less reactive compound.

• The least reactive elements are the ones that end up ‘on their own’.

• Another analogy is that more reactive elements are ‘chemical bullies’

• What would happen if a compound with bromine was mixed with a compound containing chlorine?

Some of the chemicals are toxic or harmful. Donot sniff them.Wear eye protection.

• Method1. Copy the table shown below. 2. Add about 1cm3 (about half a pipette-full) of

potassium bromide solution to the test tube. 3. Add one drop of chlorine water and gently

shake the test tube to mix the contents. 4. If you see a colour change, make a note of it

in your table.

• Method

If you do not see a colour change, add up to 9 more drops of chlorine water (remembering to shake the test tube after each drop) and make a note of any colour change in your table.

If you still do not see a colour change, write No reaction in your table.

5. Wash out your test tube. 6. Repeat steps 2 – 5 for each of the following

combinations:

• chlorine water added to potassium iodide • iodine water added to potassium chloride • bromine water added to potassium chloride • iodine water added to potassium brom. • bromine water added to potassium iodide

(circle one)

Halogen in solution

Salt in solution

Colour of top layer

Halogen in top layer

Halogen in compound

Which is most reactive?

Chlorine KBr

Chlorine KI

Iodine KCl

Iodine KBr

Bromine KCl

bromine KI

Potassium Chloride

Potassium Bromide

Potassium Iodide

Number of Reactions

Chlorine Water

Bromine Water

Iodine Water

• Count the number of reactions seen in each row and write the results in your table.

• The halogen that produces the most reactions is the most reactive of the three.

Potassium Chloride

Potassium Bromide

Potassium Iodide

Number of Reactions

Chlorine Water

No Reaction

Bromine Water

No Reaction

Iodine Water

No Reaction

Conclusions

• 1. Write the names of the halogens in order of reactivity, from the most reactive to the least.

• 2. Compare your reactivity series with Group 7 in the Periodic Table – what do you notice?

• 3. What results might you get if fluorine water and potassium fluoride were in the experiment too?

• 4. Write word equations for each of the reactions seen in the experiment.

• For example: chlorine + potassium bromide ® potassium chloride + bromine