Group 7, The Halogens Flashcards

1
Q

A student was reacting different halide ions with silver nitrate solution and studying the precipitates formed. Why did the student not bother testing fluoride ions?

A

Silver fluoride is soluble and so you don’t get a precipitate

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2
Q

What colour precipitate is produced when you react silver nitrate solution with iodide ions?

A

Pale yellow

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3
Q

What colour precipitate is produced when you react silver nitrate solution with chlorine ions?

A

White

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4
Q

What colour precipitate is produced when you react silver nitrate solution with bromine ions?

A

Cream

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5
Q

Give a simple ionic equation to show the reaction between silver nitrate solution and chlorine ions

A

Ag+(aq) + Cl-(aq) –> AgCl(s)

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6
Q

Give a simple ionic equation to show the reaction between silver nitrate solution and bromine ions

A

Ag+(aq) + Br-(aq) –> AgBr(s)

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7
Q

Give a simple ionic equation to show the reaction between silver nitrate solution and iodide ions

A

Ag+(aq) + I-(aq) –> AgI(s)

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8
Q

Give the reaction of chlorine with water to form chloride and chlorate ions

A

Cl2 + H2O HCl + HClO (chloric acid)

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9
Q

What type of reaction is that of chlorine with water? (ox, reduc etc)

A

Disproportionation

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10
Q

How could you test for the presence of chlorine?

A

Blue litmus turns red in the presence of chlorine (bleaches it)

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11
Q

Give the reaction of chlorine with water to form oxygen

A

2Cl2 + 2H2O –> 4HCl + O2

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12
Q

Give a use of chlorine in water

A

Forms bleach which sterilises water for swimming and drinking

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13
Q

Give a reaction to show the formation of bleach

A

Cl2 + 2NaOH –> NaClO (bleach) + NaCl + H2O

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14
Q

Describe and explain what you would observe if you added chlorine water to KBr

A

An orange solution is formed
Cl has displaced Br as it is a better oxidising agent, and so oxides Br- to Br2

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15
Q

Describe and explain what you would observe if you added chlorine water to KI

A

A brown solution is formed
Cl2 can oxidise the I- to I2

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16
Q

Describe and explain what you would observe if you added bromine water to KI

A

A brown solution is formed
Br2 can oxidise the I- to I2

17
Q

Give an ionic equation to show the reaction between bromine water and KI

A

Br2 + 2I- –> 2Br- + I2

18
Q

What kind of reaction is shown between the reaction of chlorine water and KBr

A

Displacement reaction
Also a redox reaction

19
Q

What kind of reaction is shown between the reaction of chlorine water and KBr

A

Displacement reaction
Also a redox reaction

20
Q

Describe and explain the trend in oxidising ability down the halogen ions

A

Decreases as you go down
Get larger - more shielding and so weakened nuclear attraction, resulting in the ion being less able to attract an electron (be reduced)

21
Q

What type of reaction is the formation of bleach (ox/redox)?

A

Disproportionation

22
Q

Why is dilute nitric acid added to a solution of halides in order to determine what ions are present?

A

to remove any other ions that could give undesired precipitates with silver nitrate