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Chemistry Year 12 > Reactivity Trends ✅ > Flashcards

Reactivity Trends ✅ Flashcards

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1
Q

What are group 2 elements in redox reactions

A

Reducing agents

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2
Q

What is created from a group 2 metal and oxygen, describe oxidation state and numbers

A

Metal oxides,
oxidation=magnesium, +2
Reduction=oxygen, -2

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3
Q

What is created from a group 2 metal and water, describe oxidation state and numbers

A

Alkaline hydroxide
Sr= oxidation, +2
Hydrogen= reduction,-2

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4
Q

What is created from a group 2 metal and dilute acids, describe oxidation state and numbers

A

Salt +hydrogen gas
Magnesium=oxidation, +2
Hydrogen=reduction,-2

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5
Q

What are the trends in reactivity (with water, oxygen, hydroxides and acids) and ionization energy In group 2

What is trend in melting point going down group 2

A

Reactivity increases down the group with all 4

Ionization energy decreases down the
Group

Melting points decreases

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6
Q

Why does reactivity increase down group 2

A

Want to be oxidized
Further away the electron is, easier it is to lose
Atomic radius increases, more electron shielding, nuclear attraction, less energy required to overcome it as they are two factors meaning it is easier to lose against one making it harder

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7
Q

What is formed from group 2 compounds and water

A

Alkaline solutions of metal hydroxide and hydroxide ions

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8
Q

How does the solubility of the hydroxides change going down group 2

A

Increases, resulting solutions contain more OH- ions and are more alkaline

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9
Q

How are group 2 compounds used in every day life

A

Neutralize acids
Agriculture (increase soil pH)
Medicine (acid indigestion)!

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10
Q

At room temp and pressure what are the halogens

A

Diatomic molecules

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11
Q

What structure does halogens that are solid have

A

Lattices with simple molecular structures

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12
Q

Why are the halogens oxidizing agents

A

Because it has oxidized another species

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13
Q

What colour are chlorine solution in water and cycohexane

A

Water: pale green
Cyclohexane: pale green

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14
Q

What colour are bromine solution in water and cycohexane

A

Water: oranje
Cyclohexane: oranje

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15
Q

What colour are iodine solution in water and cycohexane

A

Water: brown
Cyclohexane: violet

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16
Q

What order of reactivity is bromine iodine and chlorine in, so what displaces what

A

Chlorine, bromine, iodine

Chlorine displaces both, bromine only iodine

17
Q

How does reactivity change going down the group for halogens and why

A

Decreases

Atomic radius increase, more inner shells do more shielding, less nuclear attraction to capture another electron, reactivity decreases

18
Q

What is disproportionation

A

Redox reaction in which same element js both oxidized and reduced

19
Q

What type of reaction is chlorine with water and why

A

Disproportionation
Chlorine both oxidized and reduced

20
Q

What is added to test for halide ions

A

Aqueous silver ions added to aqueous halide ions to form a precipitate

21
Q

Describe the carbonate test

A

Basis for a test for the carbonate ion (CO3,^2-)

In a test tube add dilute nitric acid to solid or solution to be tested
If you see bubbles, unknown compound could be a carbonate
To prove that the gas is CO2, do limewater test (a saturated aq solution of calcium hydroxide)
CO2 reacts to form fine white precipitate or calcium carbonate, turns the solution cloudy

22
Q

Describe the sulfate test

A

Most sulfates soluble, barium sulfate isn’t
Aq barium ions are added to a solution of an unknown compound (usually barium chloride and barium nitrate, if doing a halide test after use nitrate)
A white precipitate is formed

23
Q

How to do the halide test

A

Add aq silver nitrate, to an aq solution of a halide
Silver chloride is white, silver bromide is cream, silver iodide is yellow
Adding dilute ammonia: chloride is soluable
Adding concentrated ammonia: bromide is soluble, Iodide is Insoluble

24
Q

What is the correct order to analyze an unknown inorganic compound

A

Carbonate
Sulfate
Halides

25
Q

How could you distinguish between NaCl, NaBr and NaI by a simple test (3 marks)

A

Add AgNO3 (aq) to an aq solution of each. NaCl forms a white precipitate which dissolved in dilute NH3 (aq)

NaBr forms a cream precipitate which concentrated NH3 (aq)

NaI forms a yellow precipitate which is insolvable in concentrated NH3 (aq)

26
Q

Explain why it is important to carry out the carbonate test before carrying out a sulfate test on an unknown chemical (2 marks)

A

Dilute nitric acid reacts with carbonate ions and no precipitate of barium carbonate will then form

27
Q

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 (2 marks)

A

If sulfuric acid is used, sulfate ions ate after and will show up the sulfate test with Ba 2+ (aq). If HCl acid is used, chloride ions are added and will show up in the halide test with Ag+ (aq)

28
Q

State and explain the trend in boiling points of the halogens fluorine to iodine (3 marks)

A

Boiling point increases due to increase in electrons down the group. This increases the strength of the London Forces and more energy needed to break the intermolecular forces

29
Q

Explain why group 2 elements are reducing agents (2 marks)

A

Group 2 metals add electrons to other species

30
Q

Following reaction is a redox process:
Mg+2HCl=MgCl2+H2
A: identify the changes in oxidation number
B: state which species is being oxidized and which is being reduced (3 marks)

A

A: Mg changes from 0 to +2, H changes from +1 to 0
B: Mg oxidized, H reduced

31
Q

Explain why group 2 elements become more reactive down the group (4 marks)

A

Down group 2, the total energy from 1st and 2nd ionization energies decreases as nuclear attraction on outer electrons decreases as nuclear attraction on the outer electrons decreases because of increases atomic radius and increased shielding. It therefore becomes easier to remove the electrons and the reactivity increases

32
Q

State and explain the trend in alkalinity of solution formed when group 2 oxides are added to water (3 marks)

A

Group 2 oxides react with water forming the metal hydroxide. Hydroxide ions in solution cause alkalinity. Down group 2, the solubility of the metal hydroxide increases, increasing the pH and alkalinity

33
Q

how do you test for ammonia ions

A

adding hydroxide ions eg NaOH to give NH3+H2O

34
Q

what forms from group 2 metals and oxygen

A

metal oxide

35
Q

what forms from group 2 metals and dilute acids

A

salt and hydrogen gas

Chemistry Year 12 (5 decks)

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