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A Level Chemistry > Group 7 Chapter 10 > Flashcards

Group 7 Chapter 10 Flashcards

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1
Q

At room temperature what is fluorine like?

A

A pale yellow gas.

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2
Q

At room temperature what is chlorine like?

A

A pale green gas.

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3
Q

At room temperature what is bromine like?

A

A red-brown liquid.

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4
Q

At room temperature what is iodine like?

A

A black solid?

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5
Q

What is the trend in appearances going down group 7, why?

A

Darker and denser, larger m.p and b.p down the group and less volatile down the group.

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6
Q

What is the trend in size of atoms down group 7, why?

A

Bigger down the group, extra electron shell filled.

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7
Q

What is the trend in electronegativity going down group 7, why?

A

Decreases, bigger the atoms the more the nucleus is shielded by extra inner e-s meaning effect of nuclear charge is reduced and so is the nucleus’ ability to attract the pair of e-s.

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8
Q

What is the trend of melting and boiling points down group 7, why?

A

Increase, larger atoms have more e-s making VDW forces between molecules stronger.

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9
Q

How do halogens usually react, what does this make them . What sort of reaction is this and why?

A

React by stealing e-s to become negative ions. This is a redox reaction as halogens are oxidising agents and are themselves reduced.

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10
Q

What is the trend in oxidising ability of halogens going down the group?

A

Decreases down the group, increases up the group.

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11
Q

What halogen is one of the best oxidising agents known?

A

Fluorine.

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12
Q

How do halogens react with metal halides in solution?

A

The halide in the compound will be displaced by the more reactive halogen, displacement reaction.

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13
Q

Does F2 oxidise Cl-?

A

Yes.

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14
Q

Does F2 oxidise Br-?

A

Yes.

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15
Q

Does F2 oxidise I-?

A

Yes.

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16
Q

Does Cl2 oxidise F-?

A

No.

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17
Q

Does Cl2 oxidise Br-, what does it produce and what is the equation?

A

Yes, yellow/ orange solution. Cl2(aq) + 2Br-(aq) -> 2Cl2-(aq) + Br2(aq).

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18
Q

Does Cl2 oxidise I-, what does it produce and what is the equation?

A

Yes, brown solution and black precipitate. Cl2(aq) + 2I- -> 2Cl-(aq) + I2(aq).

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19
Q

Does Br2 oxidise F-?

A

No.

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20
Q

Does Br2 oxidise Cl-?

A

No.

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21
Q

Does Br2 oxidise I-, what does it produce and what is the equation?

A

Yes, brown solution and black precipitate. Br2(aq) + 2I-(aq) -> 2Br-(aq) + I2(aq)

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22
Q

Does I2 oxidise F-?

A

No.

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23
Q

Does I2 oxidise Cl-?

A

No.

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24
Q

Does I2 oxidise Br-?

A

No.

25
Q

Which halogen is the weakest oxidiser?

A

Iodine.

26
Q

Which halogen is the strongest oxidiser?

A

Fluorine.

27
Q

When displacing a species, when the weaker one is left alone what is its state?

A

Solid.

28
Q

When a halide ion reduces another substance, what happens and what is the general equation?

A

Halide is oxidised to a halogen, 2X- -> X2 + 2e-`

29
Q

What is the trend in reducing power down group 7 halides, why?

A

Increases, larger the ion the easier it is to lose e-s.

30
Q

How do we test the reducing power of the halides?

A

Solid Na halides react with concentrated sulphuric acid. he products are different and reflect their reducing power.

31
Q

Drops of sulfuric acid are added to sodium CHLORIDE, what is the product? What type of reaction is this and what is the equation?

A

Produces steamy fumes of HCl, the solid product is sodium hydrogen sulphate. This is an acid-base reaction and the equation is NaCl + H2SO4 -> NaHSO4 + HCl.

32
Q

Is the reaction with sodium chloride a redox, why or why not?

A

No, no oxidation state has changed.

33
Q

Drops of sulfuric acid are added to sodium BROMIDE, what are the products? What type of reactions are these and what are the equations?

A

Steamy fumes of HBr, brown fumes of Br2, colourless SO2. Acid-base of HBr (same equation as general). Oxidation of Br-, 2Br- + H2SO4 + 2H+ -> Br2 + SO2 + 2H2O. Sulphuric acid reduction for SO2, 2H+ + 2Br- + H2SO4(l) -> SO2(g) + 2H2O(l) + Br2(l).

34
Q

Drops of sulfuric acid are added to sodium IODIDE, what are the products? What type of reactions are these and what are the equations?

A

Steamy fumes of sodium iodide, black solid of iodine, bad egg smell of hydrogen sulphide, yellow solid sulphur. Hydrogen iodide is an acid-base reaction. SO2, S and hydrogen sulphide are reduced by iodide ions, 8H+ + 8I- + H2SO4(l) -> H2S(g) + 4H2O(l) + 4I2(s).

35
Q

How else can we identify the halides?

A

Using their reactions with silver ions.

36
Q

What are the steps to identifying a halide with silver ions?

A

Dilute nitric acid is added to the halide to remove any soluble carbonate or hydroxide impurities. A few drops of silver nitrate is added and a precipitate forms.

37
Q

How would carbonate or hydroxide impurities interfere with the test for identifying halides using silver ions.

A

By forming insoluble silver carbonate or insoluble silver hydroxide.

38
Q

For silver fluoride what precipitate do we see?

A

None.

39
Q

For silver chloride what precipitate can we see? What happens dilute ammonia is added?

A

White precipitate, dissolves.

40
Q

For silver bromide what precipitate do we see? How does it interact with dilute and conc. ammonia?

A

Cream precipitate, dissolves in conc. ammonia.

41
Q

For silver iodide what precipitate do we see? What happens when dilute or conc. ammonia is added?

A

Pale yellow precipitate, doesn’t dissolve in either ammonias.

42
Q

Why doesn’t fluorine form a precipitate?

A

It’s soluble in water.

43
Q

What is the general equation for an acid-base reaction?

A

NaX(s) + H2SO4(l) -> NaHSO4(s) + HX(g)

44
Q

What is the general equation for silver nitrate added to an acidified solution to test for a halide?

A

AgNO3(aq) + NaX(aq) -> NaNO3(aq) + AgX(s).

45
Q

What do we use chlorine to do, why?

A

Treat drinking water and swimming pools, kills bacteria by oxidation.

46
Q

How does chlorine react with water, what sort of reaction is this and what does it produce? What is the equation?

A

Dissolves in a reversible reaction to produce chloric (I) acid, HClO and HCl. Cl2(g) + H2O(l) -> HCl(aq) _ HOCl(aq).

47
Q

What sort of reaction is happening when chlorine dissolves in water, why?

A

Disproportionation, one Cl is being reduced and the other oxidised.

48
Q

Define disproportionation.

A

Simultaneous oxidation and reduction of a species.

49
Q

How does chlorine react with cold, dilute sodium hydroxide (an alkali). What does it produce, what is the equation? What sort of reaction is this another example of?

A

Produces sodium chlorate NaClO, Cl2(g) + 2NaOH(aq) -> NaCl(aq) + NaOCl (aq) + H2O(l). Disproportionation.

50
Q

What is the equation when an aqueous solution of chlorine is left in the sunlight?

A

2Cl2(g) + 2H2O(l) -> 4HCl(aq) + O2(g)

51
Q

Sodium bromide reacts with concentrated sulfuric acid, write an equation for this reaction of sodium bromide.

A

2NaBr + 2H2SO4 -> Na2SO4 + Br2 + SO2 + 2H2O

52
Q

A colourless solution contains a mixture of sodium chloride and sodium bromide.
Using aqueous silver nitrate and any other reagents of your choice, develop a procedure to prepare a pure sample of silver bromide from this mixture.
Explain each step in the procedure and illustrate your explanations with equations, where appropriate.

A

Add silver nitrate to form ppts of AgCl and AgBr, AgNO3 + NaCl -> AgCl + NaNO3, AgNO3 + NaBr -> AgBr + NaNO3. Add excess of dilute ammonia to the mixture of ppts. The AgCl dissolves, AgCl + 2NH3 -> [Ag(NH3)2]+ + Cl-, filter off remaining AgBr ppt, wash to remove soluble compounds, dry to remove water.

53
Q

Write an ionic equation for the reaction between chlorine and cold dilute sodium hydroxide solution.

A

Cl2 + 2HO- -> OCl- + Cl– + H2O

54
Q

Chlorine gas is bubbled through a solution containing bromide ions. What would you observe?

A

Turns to orange solution.

55
Q

Explain why chlorine has a lower boiling point than bromine.

A

Br is bigger than Cl, has more e-s. Cl2 has weaker VDW forces between molecules making it easier and requiring less energy to break/ boil.

56
Q

Write an equation for the reaction between strontium chloride solution and sodium sulfate solution.

A

SrCl2(aq) + Na2SO4(aq) -> SrSO4(aq) + NaBr(aq)

57
Q

Describe briefly how you could obtain strontium sulfate from a mixture of strontium carbonate and strontium sulfate.

A

Add nitric acid to mixture, filter.

58
Q

Explain why drinking magnesium sulfate solution is effective in the treatment of barium poisoning.

A

Insoluble BaSO4 formed, removes barium ions as a ppt.

A Level Chemistry (26 decks)

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