ES

Question 1

halogens

Answer 1

group 7 elements
7 electrons in outer shell
most reactive group of non-metals
none found naturally in elemental form

Question 2

halogens in ionic compounds

Answer 2

gains an electron from a metal ion to form a halide ion in an ionic compound

Question 3

colours and physical states of diatomic halogens

Answer 3

F2 - pale yellow gas at room temperature
Cl2 - green gas at room temperature
Br2 - dark red volatile liquid
I2 - shiny grey solid

Question 4

going down the group halogens…

Answer 4

become darker in colour
MP and BP decrease
become less volatile
decrease in reactivity

Question 5

strongest oxidising agent HALOGEN

Answer 5

decreases down group - fluorine most oxidising

Question 6

a halogen can displace a

Answer 6

less reactive halide (eg. fluorine can displace iodide)

Question 7

oxidation

Answer 7

gaining oxygen
loss of hydrogen
loss of electrons
ON increases

Question 8

reduction

Answer 8

loss of oxygen
gaining hydrogen
gaining electrons
ON decreases

Question 9

oxidising agents vs reducing agents

Answer 9

oxidising agents - oxidise others by accepting electrons, are themselves reduced

reducing agents - reduce others by donating electrons, are themselves oxidised

Question 10

systematic names

Answer 10

include oxidation state of elements/ions with variable oxidation states eg. transition metals

Question 11

cathode

Answer 11

negative electrode

cations (+ve) ARE REDUCED

Question 12

anode

Answer 12

positive electrode

anions (-ve) ARE OXIDISED

Question 13

oxidation of water

Answer 13

H2O&raquo_space; O2 + 4e- + 4H+

at anode

Question 14

reduction of water

Answer 14

2H2O + 2e-&raquo_space; 2OH- + H2

at cathode

Question 15

conditions for oxidation of water in electrolysis

Answer 15

O2 produced if salt is sulfate or nitrate

halogen produced if salt is halide

Question 16

conditions for reduction of water in electrolysis

Answer 16

H2 produced if metal is group 1 or 2, aluminium, or an acide is being electrolysed
(if none of above metal is plated)

Question 17

electrolysis of hydroxides

Answer 17

4OH-&raquo_space; O2 + H2O + 2e-

at the ANODE

Question 18

dynamic equilibrium

Answer 18

concentrations of reactants and products remain constant
forward and reverse reactions both occuring
rate of forwards reaction = rate of reverse reaction

Question 19

if dynamic equilibrium is disturbed by altering the conditions

Answer 19

position of equilibrium will shift to counteract the change

Question 20

increase in availability of reactants causes equilibrium to

Answer 20

shift to right

Question 21

increase in availability of products causes equilibrium to

Answer 21

shift to left

Question 22

increasing temperature causes equilibrium to

Answer 22

shift to favour ENDOTHERMIC reaction

Question 23

increasing pressure causes equilibrium to

Answer 23

shift to side of reaction which produces fewer moles of gas

Question 24

Kc =

Answer 24

[products] / [reactants]

equilibrium constant

Question 25

Kc > 1

Answer 25

equilibrium lies to right | and if Kc > 10^10 reaction gone to completion

Question 26

uses of chlorine

Answer 26

sterilising water by killing bacteria | bleaching

Question 27

risks of chlorine

Answer 27

TOXIC gas - irritate eyes, lungs and respiratory system can react in lungs to produce HCl transported in tanks - if damp inside tanks HCl forms stored in cylinders which are moved using a hoist to avoid damage transported as liquid - more stored in smaller volume can be transported by road/rail

Question 28

purpose of iodine-thiosulfate titrations

Answer 28

find the conc of a chemical that is a strong enough oxidising agent to oxidise iodide ions

Question 29

thermal stability of hydrogen halides

Answer 29

decreases down group (more stable at top - hydrogen fluoride) bond strength between hydrogen and halide decreases down group 7

Question 30

acidity of hydrogen halides

Answer 30

very acidic in solution with exception of H-F | for others there is almost 100% dissociation producing oxonium ions

Question 31

reaction of hydrogen halides with ammonia

Answer 31

all react with ammonia to form salts | NH3 (g) + HCl (g) >> NH4Cl (s)

Question 32

reactions of hydrogen halides with sulfuric acid

Answer 32

all different due to increasing strength of halides as reducing agents HF and HCl don't react HBr makes SO2 HI makes H2S

Question 33

strength of reducing agents HALIDES

Answer 33

increases down group - iodide most reducing

Question 34

producing hydrogen halides from sodium halides

Answer 34

a reaction of NaF/NaCl with H2SO4 can be used to produce HF/HCl phosphoric acid has to be used to produce HBr/HI because it won't be reduced by bromide/iodide