Creative Chemistry: Saunders N. 2000: Creative Chemistry

985 Words 4 Pages
Ref: Saunders N. 2000, Creative Chemistry
You have seen that the Group 1 alkali metal elements increase in reactivity as you go down the group. Sodium is less reactive than potassium, which is less reactive than rubidium (which you weren’t allowed to observe directly!) Today, you will use displacement reactions to work out the order of reactivity of the Group 17 halogen elements using chlorine, bromine and iodine.

The higher on the periodic table the more reactive the element will be.


Safety glasses
0.2M potassium chloride solution
Black tray
0.2M potassium bromide solution
Spotting tile
0.2M potassium iodide solution
Teat pipette chlorine water
Distilled water bromine water

Iodine water

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This was because they were the same chemical compound.

Summarise the results obtained for each halogen.
Potassium Chlorine and Chlorine had no reaction.
Potassium Chlorine and Bromine changed the colour to a light yellow colour.
Potassium chloride and iodine changed the colour to a dark yellow.
Potassium bromide and chlorine change the colour to a light orange yellowish colour.
Potassium bromide and bromine had no reaction.
Potassium bromide and iodine changed the colour to an orange brownish colour.
Potassium iodide and Chlorine changed the colour to a red brown.
Potassium iodide and Bromine changed the colour to a red dark orange colour.
Potassium iodide and iodine had no reaction.

Write word equations for the combinations that DID result in a displacement reaction occurring (i.e. a definite colour change was observed) Potassium chloride + Bromine = Potassium Bromide + Chlorine
Potassium chloride + Iodine = Potassium iodide + Chlorine
Potassium Bromide + Chlorine = Potassium Chloride + Bromine
Potassium Bromide + Iodine = Potassium Iodide +
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Iodine > Bromine > Chlorine.

Describe the trend in reactivity of the Group 17 elements compared to their order on the periodic table.

The higher the element on the periodic table the more reactive they will be.

Explain how the trend in reactivity is related to the trends in electronegativity and atomic radii down a group.

The higher the electronegativity and the smaller the atomic radii the more reactive the element will be when compare to elements with higher atomic radii and lower electronegativity.

What results would you expect if fluorine water and potassium fluoride were available to test?
Predict what would occur in the following mixtures. If a reaction would occur, write the names of any products formed. If no reaction, state “no reaction”.
Fluorine + potassium chloride → Potassium Fluoride + Chlorine
Fluorine + potassium bromide → Potassium Fluoride + Bromine
Fluorine + potassium iodide → Potassium Fluorine + Iodine
State at least two possible sources of error in this experiment.

Errors could come from the Pitette not being accurate, having a process which made this more accurate could improve the results of this experiment. Another reason for errors could be human error where someone misjudged the colour of a reaction and recorded the wrong

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