Elements of the SEA

Question 1

Effect of temperature on Kc

Answer 1

If temp added- Equilibrium will shift in the endothermic direction to absorb the heat
If temp decreased - equilibrium shifts in the exothermic direction
Increasing temp decreases Kc value

Question 2

Trends down group 7 (the halogens)

Answer 2

Less volatile due to increasing id-ids as size and relative mass of the atoms increase
In natural state they’re covalent diatomic molecules with a low solubility in water but they dissolve easily in organic solvents
Less reactive down the group
Oxidising agents

Question 3

Halogens appearance at RTP

Answer 3

Fluorine - pale yellow gas
Chlorine - yellow-green gas
Bromine - red-brown liquid
Iodine - shiny grey solid

Question 4

Colours of the halogens when dissolved in organic solvents

Answer 4

Chlorine - colourless
Bromine - orange/red
Iodine - pink/violet

Question 5

Colours of the halogens when dissolved in water

Answer 5

Chlorine - colourless
Bromine - yellow/orange
Iodine - brown

Question 6

Why are halogens less reactive?

Answer 6

Atoms larger
Electrons further from nucleus
Outer electrons more shielded from positive nucleus as there are more inner electorns
This makes it harder for larger atoms needed to attract the electron to form an ion

Question 7

Displacement reactions

Answer 7

A more reactive halogen will replace a less reactive halide in solution

Question 8

Reaction of bromine, iodine and chlorine water with potassium chloride solution

Answer 8

No reaction

Question 9

Reaction of bromine, iodine and chlorine water with potassium bromide solution

Answer 9

No reaction with bromine and iodine
Cl2 + 2Br- -> 2Cl- +Br2

Question 10

Reaction of bromine, iodine and chlorine water with potassium iodide solution

Answer 10

No reaction with iodine
Cl2 + 2I-
Br2 + 2I-