Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

chemistry > C8 - Reactivity trends > Flashcards

C8 - Reactivity trends Flashcards

You may prefer our related Brainscape-certified flashcards:
Periodic Table flashcards Chemistry 101 flashcards AP® Chemistry flashcards Organic Chemistry 101 flashcards
1
Q

What is group 2 called?

A

Alkaline earth metals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are group 2 elements used as?

A

Reducing agents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What happens to group 2 elements during redox reactions?

A

Oxidised
Acts as a reducing agent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Half equation for redox reaction of group 2 metal

A

M –> M2+ + 2e-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What happens to the reactivity of group 2 metals down the group?

A

Increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Equation for group 2 element plus water?

A

M + 2H2O –> M(OH)2 + H2

Metal + water —> metal hydroxide + hydrogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What happens during redox reactions of group 2 metals and water?

A

Group 2 metal is oxidised
2 atoms of H reduced and other 2 do not change

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Group 2 metal plus dilute acid

A

metal + acid –> salt + H2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What happens during redox reaction of group 2 metal and a dilute acid

A

Metal is oxidised
Hydrogen is reduced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why does the reactivity of group 2 metals increase down the group?

A

Losing 2 e- and forming 2+ ions require input of first and second ionisation energies
Ionisation energies decrease down the group so are easier to overcome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Why do ionisation energies decrease down group 2?

A

Attraction between nucleus and outer shell electrons decrease:
-Increasing atomic radius
-Increasing shielding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What happens to the strength of reducing agents down group 2?

A

Increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Group 2 oxides + water

A

MO + H2O –> M2+ + 2OH-
(when solution becomes saturated: M2+ + 2OH- –> M(OH)2)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What happens to the solubility and alkalinity of group 2 hydroxides down the group?

A

Increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How can you show solubility and alkalinity of group 2 hydroxides increase down the group?

A

1) Add a spatula of each Group 2 hydroxide to water in a test tube
2) Shake mixture. You will have a saturated solution of each metal hydroxide and white precipitate.
3) Measure the pH of each solution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are group 2 oxides, hydroxides and carbonates used for?

A

As a base, to neutralise acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are group 2 compounds used for?

A

Lime to neutralise soil
Antacids to treat indigestion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How are group 2 compounds used in agriculture?

A

Ca(OH)2 added to fields as lime to increase pH of acidic soils
Ca(OH)2 + 2H+ –> Ca2+ + 2H2O

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How are group 2 compounds used in medicine?

A

Many antacids/indigestion tablets use Mg/CaCO3
Milk of magnesia is a suspension of white Mg(OH)2 in water

Mg(OH)2 + 2HCl –> MgCl2 + 2H2O
CaCO3 + 2HCl –> CaCl2 –> H2O + CO2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Is Mg(OH)2 soluble in water?

A

Only slightly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is group 7 known as?

A

Halogens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What happens to boiling points down group 7?

A

Increases, because of London forces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How do group 7 elements exist at room temperature?

A

Diatomic molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Why do boiling points increase down group 7?

A

-More electrons
-Stronger London forces
-More energy required to break intermolecular forces
-Boiling point increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How does fluorine exist at RTP?

A

Pale yellow gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

How does chlorine exist at RTP?

A

Pale green gas

27
Q

How does bromine exist at RTP?

A

Red-brown liquid

28
Q

How does iodine exist at RTP?

A

Shiny grey-black solid

28
Q

What happens to halogens during redox reactions?

A

Reduced, oxidising agents

29
Q

Half equation for halogens

A

X2 + 2e- –> 2X-

30
Q

How can you test the reactivity of halogens?

A

Halogen-halide displacement reactions

31
Q

What happens to the reactivity of halogens down the group?

A

Decreases

32
Q

How do you do a halogen-halide displacement reaction?

A

-Solution of each halogen is added aqueous solutions of the other two halides
-Halogen displaces halide causing solution to change colour
-Iodine and bromine in water can appear similar orange-brown colour
-Organic non-polar solvent (cyclohexane) added and mixture shaken
-Non-polar halogens dissolve more readily in cyclohexane and colour change occurs

33
Q

Reaction between chlorine water and bromide solution

A

Pale green to orange as Br2 formed
Cl2 + 2Br- –> 2Cl- + Br2

34
Q

Reaction between chlorine water and iodide solution

A

Pale green to violet as I2 formed
Cl2 + 2I- –> 2Cl- + I2

35
Q

Reaction between bromine water and chloride solution

A

No reaction

36
Q

Reaction between bromine water and iodide solution

A

Orange to violet from I2 formed
Br2 + 2I- –> 2Br- + I2

37
Q

Reaction between iodine water and chloride solution

A

no reaction

38
Q

Reaction between iodine water and bromide solution

A

No reaction

39
Q

How does astatine exist at RTP?

A

Radioactive, never been seen

40
Q

Why does the reactivity decrease down group 7?

A

-Atomic radius increases
-More inner shells so shielding increases
-Less nuclear attraction
-Reactivity decreases

41
Q

What happens to the oxidising ability down group 7?

A

Decreases

42
Q

What is disproportionation

A

Redox reaction in which the same element is both oxidised and reduced

43
Q

Reaction of chlorine with water

A

Cl2 + H2O –> HClO + HCl

44
Q

What is chlorine used for?

A

Water purification

45
Q

What is HClO called?

A

Chloric (I) acid

46
Q

How does chlorine purify water?

A

Chloric (I) acid and chlorate (I) ions kill bacteria

47
Q

Reaction of chlorine with cold, dilute sodium hydroxide

A

Cl2 + 2NaOH –> NaClO + NaCl + H2O

48
Q

What use does the reaction of chlorine with cold, dilute sodium hydroxide serve?

A

Household bleach

49
Q

What are the risks of chlorine use?

A

-Respiratory irritant and can be fatal
-Toxic gas
-Can react with organic hydrocarbons producing chlorinated hydrocarbons which may cause cancer

50
Q

Why is chlorine still used to purify water considering risks?

A

Risks of not adding chlorine to water are far greater

51
Q

What is the test for halide ions?

A

1) Add silver nitrate solution
2) Precipitate is formed
Ag+ + X- –> AgX

52
Q

What is the carbonate test?

A

Carbonate reacts with acids to form CO2
1) In a test tube, add dilute nitric acid to sample
2) If there is effervescence, could be a carbonate
3) Test for carbon dioxide by bubbling through Ca(OH)

53
Q

What is the test for carbon dioxide?

A

1) Bubble gas through limewater (saturated solution of Ca(OH)2)
2) Carbon dioxide reacts to form white precipitate of CaCO3, turning limewater cloudy

54
Q

What is a sulfate test?

A

1) Barium nitrate added to sample
2) If white precipitate formed, sulfate is present

55
Q

Ionic equation for formation of barium sulfate?

A

Ba2+ + SO42- –> BaSO4

56
Q

What is a halide test?

A

1) Add aqueous silver nitrate to sample
2) Halide precipitates are different colours
3) Add aqueous ammonia to test solubility of precipitate

57
Q

Halide test results

A

Chloride - white, soluble in dilute NH3
Bromide - cream, soluble in conc NH3
Iodide - yellow, insoluble in conc NH3

58
Q

What sequence do you carry out these tests?

A

1) Carbonate, CO3 2-
2) Sulfate, SO4 2-
3) Halides, Cl- Br- I-

59
Q

Why is carbonate test first

A

-Add a dilute acid, looking for effervescence
-Neither sulfate or halide ions bubble with dilute acids
-If test produces no bubbles, continue to next test

60
Q

Why is sulfate test 2nd

A

-Add solution containing Ba+ ions, forms white precipitate of BaSO4
-BaCO3 is also a white precipitate, so if sulfate test carried out on carbonate test will be positive
-So, test should be carried out when you know no carbonate is present

61
Q

Why is halide test last?

A

-Add solution containing Ag+ ions, looking for precipitate
-Both Ag2CO3 and Ag2SO4 are precipitates
-So test should be carried out last

62
Q

How do you test a mixture of ions?

A

1) Carbonate test
-Add dilute nitric acid until bubbling stops
-All carbonate ions would have then been removed
2) Sulfate test
-Add excess of Ba(NO3)2 to solution left
-Filter solution to remove BaSO4
3) Halide test
-Add AgNO3 to solution left
-Carbonate and sulfate ions removed so precipitates involve halides
-Add NH3 to confirm halids

63
Q

How do you test for an ammonium ion?

A

1) Aqueous NaOH added to solution of ammonium ions
2) Ammonia gas produced
3) Mixture is warmed and ammonia gas released
4) Test with moist pH indicator, should turn blue

chemistry (21 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions