Inorganic Chemistry

Question 1

Group 2 metals reaction with water (cold water)

Answer 1

• Group 2 Metals react with water to form Hydrogen gas and a Metal Hydroxide (base)
  -The reactivity of group 2 metals increases down the group because of increased shielding and atomic radius (Be doesn’t react and Mg reacts slowly… the rest bubble)

Question 2

Group 2 metals reaction with oxygen

Answer 2

-Group 2 metals reacts with oxygen to form metal oxides
-They are all white solids

Question 3

Group 2 metals reactions with chlorine

Answer 3

-Group 2 elements react with chlorine to form metal chlorides
-They react more vigorously down the group
-They are all white precipitates

Question 4

Group 2 oxides reactions with water

Answer 4

-Group 2 metal oxides form a metal hydroxide when reacted with water (bases)
-This is very vigorous and exothermic and some water is evaporated
-No Hydrogen gas is given off

Question 5

Group 2 metals reaction with water (steam)

Answer 5

-Group 2 metals react vigorously with steam to produce a metal oxide and hydrogen gas
-Metal oxide is produced rather than metal hydroxide, because in the high Tempereture, the metal hydroxide thermally decomposes to the metal oxide and Hydrogen gas

Question 6

Group 2 metals reactions with dilute acids

Answer 6

-Group 2 metals react with dilute acids to form hydrogen gas and solutions of metal compounds (salts)

Question 7

Group 2 hydroxides reactions with dilute acid

Answer 7

-Group 2 hydroxides react with dilute acid to form a salt + water
-This is a neutralisation reaction
-Examples are; Magnesium hydroxide used in antacids to neutralise stomach acid and Calcium hydroxide used to neutralise soil

Question 8

Solubility of group 2 hydroxides

Answer 8

-Solubility of group 2 hydroxides increases down the group
-Magnesium hydroxides is sparingly soluble and forms a precipitate with water

Question 9

Solubility of group 2 sulphates

Answer 9

-Group 2 sulphates decreases in solubility down a group
-Barium sulphate is often used as tracer in medical scanning techniques as it cannot be absorbed by the blood (its insoluble)

Question 10

Thermal decomposition of Group 2 carbonates

Answer 10

-Group 2 carbonates heated in an aerobic condition produces carbon dioxide and a metal oxide (white powder)
-More heat is required down the group as the ions increases in size and carbonates in thermal stability

Question 11

Thermal decomposition of group 2 nitrates

Answer 11

-Group 2 decomposes to form Nitrogen dioxide, Oxygen and a Metal oxide (white powder)
-More heat is required as you go down the group as a the ion becomes bigger and the nitrates increase in thermal stability

Question 12

How can we test for Sulphate ions?

Answer 12

-Barium Chloride is used to test for Sulphates (ions)
-The method goes; We add concentrated HCl to the solution to remove carbonates as they can precipitate out after adding barium chloride giving a false results. We then add barium chloride.
-If the solution forms a white precipitate, sulphate ions are present
-This is barium sulphate, it is insoluble

Question 13

What colour does Magnesium burn (flame test)

Answer 13

No colour

Question 14

What colour does Calcium burn (flame test)

Answer 14

Brick red

Question 15

What colour does strontium burn (flame test)

Answer 15

Crimson red

Question 16

What colour does barium burn (flame test)

Answer 16

Pale green

Question 17

Why are flame tests used?

Answer 17

-Ions and metals burns with a unique colour which can be used to identify them

Question 18

How do we conduct a flame test?

Answer 18

-A Nichrome wire is cleaned with Concentrated HCl and then placed into a blue Bunsen burner (this is repeated until there is no colour change of the flame)
-Then we dip the wire into the unknown metal compound and placed into the fire to observe the colours

Question 19

Why/how do flame tests work?

Answer 19

-Flame tests work because when energy is supplied to the species, some electron will be promoted to higher energy orbitals. When they drop down to their original orbital, they release energy, some of which is emitted as light. The higher the energy released, the higher the frequency/ shorter the wavelength of light is, determining the colour

Question 20

Define Base?

Answer 20

-A proton/H+ acceptor

Question 21

Define alkali?

Answer 21

-A base that is soluble

Question 22

Define Oxidising agent

Answer 22

-A Substance that oxidised another substance by gaining electrons
-The agent themselves become reduced

Question 23

Define reducing agent

Answer 23

-A reducing agent is a substance that reduces another substance by losing electrons
-The agent itself loses electrons and is oxidised

Question 24

How does atomic radius change down the group 7 Halogens?

Answer 24

-Atomic radius increases due to additional electron shells

Question 25

How does Electronegativity change down the group 7 Halogens?

Answer 25

-Electronegativity decreases down the group as the increased atomic radius and shielding attracts the electrons in the outer shell less

Question 26

How does Melting and Boiling point change down the group 7 Halogens?

Answer 26

-M.P and B.P increases down the group as the London forces between the simple covalent Halogens increases with the relative atomic mass of the molecule (more electrons) so therefore requires more energy to overcome

Question 27

How does Reactivity change down the group 7 metals?

Answer 27

-Reactivity decreases down the group as Halogens need to gain an electron, which becomes harder to do because the increased shielding and atomic radius weakens the positive attraction the nucleus

Question 28

Halogens as oxidising agents

Answer 28

-The Halogens act as good oxidising agents as they accept electrons from the species being oxidised and they themselves are reduced
-This Oxidising power decreases down the group due to atomic radius and shielding

Question 29

Oxidising power of the Halogens

Answer 29

-They are good oxidising agents
-The oxidising power decreases down the group as their ability to attract electrons decreases due to shielding and a greater atomic radius
-The relative oxidising strengths (decreasing down the group) means that a halogen will displace any halide (Halogen ion) beneath it in the periodic table, e.g. Cl2 will displace Br- and I- ions and F will displace Cl-, Br- and I- ions

Question 30

Define Halide ions

Answer 30

-The negative ions of the Halogens

Question 31

Halide ions as reducing agents

Answer 31

-Halide ions are good reducing agents as they donate electrons to the species being reduced, they themselves being oxidised
-The reducing power increases down the group as the electrons are less strongly attracted to the positive nucleus due to increased atomic radius and shielding