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Chemistry > 2.3 Halogens > Flashcards

2.3 Halogens Flashcards

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1
Q

Describe the physical state of Fluorine (F2)

A

Very pale yellow gas. It is highly reactive.

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2
Q

Describe the physical state of Chlorine (Cl2)

A

Greenish, reactive gas, poisonous in high concentrations.

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3
Q

Describe the physical state of Bromine (Br2)

A

Red liquid, that gives off dense brown/orange poisonous fumes.

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4
Q

Describe the physical state of Iodine (I2)

A

Shiny grey solid sublimes to purple gas.

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5
Q

Does the melting and boiling point increase or decrease down group 7? Why?

A

Increases down the group.

As the molecules become larger they have more electrons so have larger van Der Waals forces between the molecules. As the intermolecular forces get larger more energy has to be put into break the forces. This increases the melting and boiling points.

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6
Q

Define electronegativity.

A

Electronegativity is the relative tendency of an atom in a molecule to attract electrons in a covalent bond to itself.

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7
Q

Does the electronegativity increase or decrease down group 7? Why?

A

The electronegativity of the elements decrease.

As one goes down he group the atomic radii increases due to the increasing number of shells. The nucleus is therefore less able to attract the bonding pair of electrons.

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8
Q

Does the oxidising strength of the elements decrease or increase down group 7?

A

The oxidising strength decreases down group 7.

A halogen that is a strong oxidising agent will displace a halogen that has a lower oxidising power from one of its compounds.

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9
Q

What is an oxidising agent?

A

Oxidising agents are electron acceptors.

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10
Q

When chlorine is added to potassium chloride in a solution what is observed?

A

Very pale green solution

No reaction

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11
Q

When bromine is added to potassium chloride in a solution what is observed?

A

Yellow solution

No reaction

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12
Q

When iodine is added to potassium chloride in a solution what is observed?

A

Brown solution

No reaction

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13
Q

When iodine is added to potassium bromide in a solution what is observed?

A

Brown solution

No reaction

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14
Q

When chlorine is added to potassium bromide in a solution what is observed?

A

Yellow solution

Cl has displaced Br

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15
Q

When bromine is added to potassium bromide in a solution what is observed?

A

Yellow solution

No reaction

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16
Q

When bromine is added to potassium iodide in a solution what is observed?

A

Brown solution

Br has displaced I

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17
Q

When chlorine is added to potassium iodide in a solution what is observed?

A

Brown solution

Cl has replaced I

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18
Q

When iodine is added to potassium iodide in a solution what is observed?

A

Brown solution

No reaction

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19
Q

Read the section marked to read on page 1 in the chemrevise revision guide.

A

Got it?

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20
Q

Draw the ionic equation for the displacement of the displacement of bromide by chlorine.

And the half equations.

A

(see page 1 in the chemrevise revision guide)

1

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21
Q

Draw the ionic equation for the displacement of the displacement of iodide by chlorine.

And the half equations.

A

(see page 1 in the chemrevise revision guide)

2

22
Q

Draw the ionic equation for the displacement of the displacement of iodide by bromine.

And the half equations.

A

(see page 1 in the chemrevise revision guide)

3

23
Q

How do you test which halide ion is present in a sample?

A

The test solution is made acidic with nitric acid and then silver nitrate is added dropwise.

The silver halide precipitates can be treated with ammonia solution to help differentiate between them if the colours look similar.

24
Q

What is the role of nitric acid in the test for halide ions?

A

The role of nitric acid is to react with any carbonates present to prevent formation of the precipitate Ag2CO3. This would mask the desired observations.

(see page 1 in the chemrevise revision guide for an equation)

25
Q

What is results of a fluoride ion in the test for halide ions?

A

Fluorine produces no precipitate.

26
Q

What is results of a chloride ion in the test for halide ions?

Draw the half equation of the reaction.

A

Chlorides produce a white precipitate.

see page 1 in the chemrevise revision guide for an equation

27
Q

What is results of a bromide ion in the test for halide ions?

Draw the half equation of the reaction.

A

Bromides produce a cream precipitate.

see page 1 in the chemrevise revision guide for an equation

28
Q

What is results of a iodide ion in the test for halide ions?

Draw the half equation of the reaction.

A

Iodides produce a pale yellow precipitate.

see page 1 in the chemrevise revision guide for an equation

29
Q

What is results of a silver chloride precipitate in the test for silver halide precipitates using ammonia?

Draw the equation of the reaction.

A

Silver chloride dissolves in dilute ammonia to form a complex ion.

(see page 1 in the chemrevise revision guide for an equation)

30
Q

What is results of a silver bromide precipitate in the test for silver halide precipitates using ammonia?

Draw the equation of the reaction.

A

Silver bromide dissolves in concentrated ammonia to form a complex ion.

(see page 1 in the chemrevise revision guide for an equation)

31
Q

What is results of a silver iodide precipitate in the test for silver halide precipitates using ammonia?

Draw the equation of the reaction.

A

Silver iodide does not react with ammonia - it is too insoluble.

(see page 1 in the chemrevise revision guide for an equation)

32
Q

Does the reducing power increase or decrease down group 7? Why?

A

The reducing power of halide increases down group 7. They have a greater tendency to donate electrons. This is because as the ions get bigger it is easier for the outer electrons to be given away as the pull from the nucleus on them becomes smaller.

33
Q

What is a reducing agent?

A

A reducing agent donates electrons.

34
Q

What reactions occur between NaF and H2SO4

A

F- ions are not strong enough reducing agent to reduce the S in H2SO4. No redox reactions occur. Only acid-base reactions occur.
H2SO4 plays the role of an acid (proton donor)

35
Q

Write the equations for the acid-base reaction between NaF + H2SO4.

What are the observations?

A

(see page 2 in the chemrevise revision guide)

36
Q

Write the equations for the acid-base reaction between NaCl + H2SO4.

What are the observations?

A

(see page 2 in the chemrevise revision guide)

37
Q

Write the acid- base and redox equations for the reaction between NaBr + H2SO4.

What are the observations?

A

(see page 2 in the chemrevise revision guide)

38
Q

Write the acid- base and redox half equations for the reaction between NaBr + H2SO4.

What are the observations?

A

(see page 2 in the chemrevise revision guide)

39
Q

What is the strongest reducing agent in group 7?

A

I- ions
Br- ions
F- and Cl- ions

in decreasing order.

40
Q

Draw the 4 equations of how I- ions reduce S from H2SO4

What are the observations?

A

(see page 2 in the chemrevise revision guide)

41
Q

Draw the 4 redox half equations of how I- ions reduce S from H2SO4

What are the observations?

A

(see page 2 in the chemrevise revision guide)

42
Q

What does disproportionation mean?

A

Disproportionation is the name for a reaction where an element simultaneously oxides and reduces.

43
Q

Draw the equation for Chlorine reacting with water.

A

(see page 3 in the chemrevise revision guide)

44
Q

What would happen to the litmus paper if you placed it in a reaction with chlorine and water.

A

It will first turn red due to the acidity of both reaction products. It will then turn colourless as the HClO bleaches the colour.

(see page 3 in the chemrevise revision guide)

45
Q

Write the equation for the reaction of chlorine with water in direct sunlight.

A

(see page 3 in the chemrevise revision guide)

46
Q

What is chlorine used for?

A

Chlorine is used in water treatment to kill bacteria. It has been used to treat drinking water and the water in swimming pool. The benefit to health of water treatment by chlorine outweigh its toxic effects.

47
Q

Write the equation for the reaction of chlorine with cold dilute NaOH solution.

A

(see page 3 in the chemrevise revision guide)

48
Q

What is a mixture of NaCl and NaClO used for?

A

Used as a bleach and to disinfect/kill bacteria

49
Q

Name NaClO

A

sodium chlorate(I)

50
Q

Name NaClO3

A

sodium chlorate(V)

51
Q

Name K2SO4

A

potassium sulfate(VI)

52
Q

Name K2SO3

A

potassium sulfate(IV)

Chemistry (36 decks)

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