Reactivity Trends ✅

Question 1

What are group 2 elements in redox reactions

Answer 1

Reducing agents

Question 2

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

Answer 2

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

Question 3

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

Answer 3

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

Question 4

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

Answer 4

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

Question 5

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

Answer 5

Reactivity increases down the group with all 4

Ionization energy decreases down the
Group

Melting points decreases

Question 6

Why does reactivity increase down group 2

Answer 6

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

Question 7

What is formed from group 2 compounds and water

Answer 7

Alkaline solutions of metal hydroxide and hydroxide ions

Question 8

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

Answer 8

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

Question 9

How are group 2 compounds used in every day life

Answer 9

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

Question 10

At room temp and pressure what are the halogens

Answer 10

Diatomic molecules

Question 11

What structure does halogens that are solid have

Answer 11

Lattices with simple molecular structures

Question 12

Why are the halogens oxidizing agents

Answer 12

Because it has oxidized another species

Question 13

What colour are chlorine solution in water and cycohexane

Answer 13

Water: pale green
Cyclohexane: pale green

Question 14

What colour are bromine solution in water and cycohexane

Answer 14

Water: oranje
Cyclohexane: oranje

Question 15

What colour are iodine solution in water and cycohexane

Answer 15

Water: brown
Cyclohexane: violet

Question 16

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

Answer 16

Chlorine, bromine, iodine

Chlorine displaces both, bromine only iodine

Question 17

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

Answer 17

Decreases

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

Question 18

What is disproportionation

Answer 18

Redox reaction in which same element js both oxidized and reduced

Question 19

What type of reaction is chlorine with water and why

Answer 19

Disproportionation
Chlorine both oxidized and reduced

Question 20

What is added to test for halide ions

Answer 20

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

Question 21

Describe the carbonate test

Answer 21

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

Question 22

Describe the sulfate test

Answer 22

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

Question 23

How to do the halide test

Answer 23

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

Question 24

What is the correct order to analyze an unknown inorganic compound

Answer 24

Carbonate
Sulfate
Halides

Question 25

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

Answer 25

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)

Question 26

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

Answer 26

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

Question 27

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)

Answer 27

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)

Question 28

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

Answer 28

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

Question 29

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

Answer 29

Group 2 metals add electrons to other species

Question 30

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)

Answer 30

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

Question 31

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

Answer 31

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

Question 32

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

Answer 32

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

Question 33

how do you test for ammonia ions

Answer 33

adding hydroxide ions eg NaOH to give NH3+H2O

Question 34

what forms from group 2 metals and oxygen

Answer 34

metal oxide

Question 35

what forms from group 2 metals and dilute acids

Answer 35

salt and hydrogen gas