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Chapter 8 - Reactivity Trends Flashcards

Group 2, The halogens and Quantitative analysis.

1
Q

What is a reducing agent?

A

A species that donates it’s electrons to another species, thereby reducing that species.

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2
Q

Which group are reducing agents commonly found?

A

Group 2

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3
Q

What is the trend in reactivity down group 2?

A

Reactivity increases.

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4
Q

Explain the trend of reactivity down group 2

A

There is increased atomic radius and shielding effect, therefore ionisation energies decrease. Therefore it’s easier to lose electrons as the attraction between the nucleus and the outer electrons decrease.

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5
Q

What are the products of a group 2 element reacting with water?

A

Metal hydroxide and hydrogen

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6
Q

What is the product of a group 2 element reacting with oxygen?

A

Metal oxide

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7
Q

What is the trend of solubility down group 2?

A

Increases

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8
Q

Explain the trend of solubility down group 2

A

as you go down the group, the solution has a greater concentration of OH- which can form hydrogen bonds
hence solubility increases

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9
Q

Given that group 2 oxides, hydroxides and carbonates neutralise acids, what can they be referred to as?

A

Bases

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10
Q

Given that most group 2 oxides, hydroxides and carbonates are soluble in water, what are they also besides bases?

A

Alkalis

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11
Q

What is the use of calcium hydroxide in agriculture?

A

Increases the pH of acidic soils.

Ca(OH)(2) + 2H+ -> Ca2+ + 2H(2)O

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12
Q

How are group 2 compounds used in medicine?

A

Used in indigestion tablets as antacids

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13
Q

What is another name for group 2?

A

Alkaline Earth Metals

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14
Q

What is another name for group 7?

A

Halogens

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15
Q

What is the trend in boiling point down group 7?

A

Increases

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16
Q

Explain the trend in boiling point down group 7

A

More electrons,
Stronger London forces,
More energy to break intermolecular forces,
Boiling point increases.

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17
Q

What is the trend in reactivity down group 7?

A

Reactivity decreases

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18
Q

Explain the trend in reactivity down group 7

A
  • Atomic radius increases,
  • More inner shells,
  • Shielding increases,
  • Nuclear attraction decreases, harder to capture e- from another species.
  • Reactivity decreases
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19
Q

What do more reactive halogens do to less reactive halide ions?

A

Displace them

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20
Q

What can displacement reactions be used to identify?

A

Which halide is present in solution.

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21
Q

Which compound is used to test for halides?

A

Silver nitrate solution

22
Q

How can the results for a halide test be further tested?

A

Solubility in ammonia solution

23
Q

What is disproportionation?

A

A redox reaction in which the same element is both oxidised and reduced.

24
Q

Describe the test for carbonates

A
  • Add unknown compound into test tube and add nitric acid to test tube
  • Bubbling indicates carbonate might be present, so CO2 gas will be released.
  • Bubble the CO2 gas in limewater, Ca(OH)2, which will turn form a milky white ppt.
  • Confirming presence of carbonate.
25
Describe the test for sulfates
Aqueous barium ions are added to the solution. If a white precipitate forms, there is a sulfate.
26
In the halide tests, what happens to chloride with silver nitrate and then ammonia
Silver nitrate - white precipitate | Ammonia - soluble in dilute ammonia
27
In the halide tests, what happens to bromide with silver nitrate and then ammonia
Silver nitrate - cream precipitate | Ammonia - soluble in concentrated ammonia
28
In the halide tests, what happens to iodide with silver nitrate and then ammonia
Silver nitrate - yellow precipitate | Ammonia - insoluble in concentrated ammonia
29
What is the correct order for these anion tests?
Carbonate test, sulphate test, halide test
30
Why is this the correct order for anion tests carbonate, sulphate, halide?
Carbonates also form a white precipitate in the sulphate test such as barium carbonate but not vice versa. So first must rule out there isn’t any carbonates present Carbonates and sulphates form precipitates with silver nitrate. Such as Ag2CO3 and Ag2SO4.
31
Describe the test for ammonium ions
- Add source of hydroxide ions to solution to be tested, such as NaOH - If Ammonium ion (NH4+) is present, it'll react with OH-(hydroxide ion) to produce Ammonia gas (NH3) and liquid water (H20) - Heat test tube to release ammonia gas, as initially, the NH3 gas is soluble in H20. - When gas released, you may smell it, but it's easier to test with red litmus paper. - Where presence of Alkaline ammonia will turn paper from red to blue.
32
If I want to work out which halide is present in a solution what can I do
Run a displacement reaction
33
A Cl2 is added to a Br- ion. What observation will you see with and without the organic non-polar solvent cyclohexane present
Orange colour will form as the chlorine would have displaced the bromide ion With cyclohexane - you will see a orange colour
34
A Cl2 is added to a I- ion. What observation will you see with and without the non-polar cyclohexane
Brown colour change as the chlorine would have displaced the Iodine ion In cyclohexane - it is violet colour
35
Bromine is added to an I- compound what is seen, what will be seen in the presence of non-polar, organic solvent cyclohexane
Brown colour change as the bromine would have displaced the Iodine ion In cyclohexane- it would be a violet colour change
36
What colour is Cl2 in water
Pale green
37
What colour is fluorine
Pale yellow
38
Describe astatine
Rare, radioactive and decays rapidly | Least reactive halogen
39
What groups are the best oxidising event and describe the oxidising trend as you go down the group
Halogens As you go down the group the halogens become weaker oxidising agents
40
Which compounds neutralises stomach acid
Magnesium hydroxide | Calcium carbonate
41
At RTP describe chlorine, bromine and iodine
Chlorine is a pale green gas Bromine is liquid, extremely toxic, and vaporises readily Iodine is a solid with grey-black crystals
42
Show the reaction of chlorine with water and what kind of reaction is this
Cl2(aq) + H20(l) >>> HCLO(aq) + HCL(aq) Disproportionation reaction
43
Show the reaction of chlorine with cold, dilute aqueous sodium hydroxide and what kind of reaction is this
Cl2(aq) + 2NaOH(aq) >>> NaCLO(aq) + NaCl(aq) + H20(l) - Disproportionation reaction - Resulting solution contains a large conc of chlorate(I), ClO-, ions from the sodium chlorate,NaClO, that's formed.
44
What do household bleach contain
Sodium chlorate (I), NaClO made by reacting chlorine with sodium hydroxide
45
Benefits and risk of chlorine use
Disinfectant for water Ensure no disease breakout Respiratory irritant Cause cancer b/ of the formation of chlorinated hydrocarbons
46
Explain the test that would be carried out on a mixture of ions
1) Carbonate test: If you see bubbles, continue adding dilute nitric acid until the effervescence stops All carbonate ion will then have been removed and there will be none left to react in the next tests. We don’t use sulfuric acid or hydrochloric acid because it contains sulfate and chloride ions , which will show up in the sulfate and halide test 2) Sulfate test: Add an excess of Ba(NO3)2 Any sulfate ion present will precipitate out as barium sulfate Filter the solution to remove the barium sulfate 3) Halide test: For the solution left, add AgNO3 (aq) Any carbonate or sulfate ion present have already been removed. Therefore any PPT must involve halide ions. Add NH3 to confirm which halide you have
47
what are the main ingredients for antacids
calcium carbonates and magnesium hydroxide
48
what is the purpose of adding the organic solvent, cyclohexane to halogen
to see a better colour change as the halogens are more soluble
49
How could you distinguish between NaCl, NaBr, and NaI by a simple test?
``` Add AgNO3(aq) to an aqeuous solution of each - If Cl- ions are present, a white PPT will form which disolves in dilute NH3(aq) ``` - If Br- ions are present, a cream PPT will form which dissolves in conc NH3(aq) - If I- ions are present, a yellow PPT will form which is insoluble in conc NH3(aq)
50
Explain why it is important to carry out the carbonate test before carrying out a sulfate test on an unknown chemical?
Dilute nitric acid reacts with carbonate ions and no precipitate of barium carbonate will then form
51
Explain why, if you are testing a mixture, it is important to use dilute nitric acid, rather than sulfuric or hydrochloric acid, for the carbonate test?
- If sulfuric acid is used, sulfate ions are added and will show up in the sulfate test with Ba2+(aq). - If hydrochloric acid is used, chloride ions are added and will show up in the halide test with Ag+(aq).

stoopid (35 decks)

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