halogens

Question 1

F2 colours + reactivity

Answer 1

very pale yellow gas

highly reactive

Question 2

Cl2 colours + reactivity

Answer 2

greenish
reactive gas
poisonous in high con

Question 3

Br2 colours + reactivity

Answer 3

red liquid

dense brown/orange poisonous fumes

Question 4

I2 colours + reactivity

Answer 4

shiny grey solid

sublimes to purple gas

Question 5

trend in boiling + melting point

Answer 5

increases down group
molecules get larger = more electrons
=larger van der waals between molecules
larger intermolecular force = more energy needed to break forces

Question 6

define electronegativity

Answer 6

relative tendency of a molecule to attract a bonding pair of electrons to itself in a covalent bond.

Question 7

trend in electronegativity

Answer 7

decreases down group
atomic radii increases down group as no. of shells increase
= nucleus less able to attract bonding pair of electrons

Question 8

what are oxidising agents

Answer 8

electron acceptors

Question 9

does oxidising strength increase or decrease down group?

Answer 9

decrease

Question 10

what will a halogen that is a stronger oxidising agent do?

Answer 10

replace a halogen with less oxidising power

Question 11

what colour does chlorine have if it’s a free halogen in a displacement reaction

Answer 11

very pale green

Question 12

what colour does bromine have if it’s a free halogen in a displacement reaction

Answer 12

yellow solution

Question 13

what colour does iodine have if it’s a free halogen in a displacement reaction

Answer 13

brown solution

sometimes black solid

Question 14

write the half equations for the displacement reaction for Cl2(aq) + 2Br –(aq) → 2Cl –(aq) + Br2(aq)

Answer 14

2Br - (aq)→ Br2(aq)+ 2e-

Cl2(aq)+ 2e- → 2Cl- (aq)

Question 15

why is a halide ion with silver nitrate test used

Answer 15

to identify the halide ion

Question 16

what chemicals are used in a silver nitrate test

Answer 16

nitric acid - to make solution acidic

silver nitrate - added dropwise

Question 17

what is the role of nitric acid in a silver nitrate test

Answer 17

react with carbonates present

to prevent ppt of Ag2Co3- would mask desired products

Question 18

write the reaction between nitric acid and sodium carbonate

Answer 18

2 HNO3 + Na2CO3 →2 NaNO3 + H2O + CO2

Question 19

what do fluorides produce with silver nitrate and nitric acid

Answer 19

no ppt

Question 20

what do chlorides produce with silver nitrate and nitric acid

Answer 20

white ppt

Question 21

write the ionic equation for the reaction of chlorine with silver nitrate and citric acid

Answer 21

Ag+(aq) + Cl- (aq) → AgCl(s)

Question 22

what do bromides produce with silver nitrate and nitric acid

Answer 22

cream ppt

Question 23

write the ionic equation for the reaction of bromine with silver nitrate and citric acid

Answer 23

Ag+(aq) + Br- (aq) → AgBr(s)

Question 24

what do iodides produce with silver nitrate and nitric acid

Answer 24

pale yellow ppt

Question 25

write the ionic equation for the reaction of iodine with silver nitrate and citric acid

Answer 25

Ag+(aq) + I- (aq) → AgI(s)

Question 26

what does silver chloride dissolve in

Answer 26

dilute ammonia

Question 27

what does silver bromide dissolve in

Answer 27

concentrated ammonia

Question 28

what does silver iodide dissolve in

Answer 28

doesn't react with ammonia - too insoluble

Question 29

trend in reducing power down the group and why

Answer 29

increasing power ions bigger, outer electrons further from positive nucleus extra inner electrons provide shielding

Question 30

what type of reaction takes place between H2SO4 and Cl and why

Answer 30

acid- base | cl is not strong enough of a reducing agent

Question 31

write the equation for the reaction between H2SO4 and Cl

Answer 31

NaCl(s) + H2SO4(l) → NaHSO4(s) + HCl(g)

Question 32

what observations in H2SO4 + Cl reaction

Answer 32

white steamy fumes | of HCL

Question 33

what type of reaction takes place between H2SO4 and F and why

Answer 33

acid- base | F is not strong enough of a reducing agent

Question 34

write the equation for the reaction between H2SO4 and F

Answer 34

NaF(s) + H2SO4(l) →NaHSO4(s) + HF(g)

Question 35

what observations in H2SO4 + F reaction

Answer 35

white steamy fumes | of HF

Question 36

what is the role of H2SO4 in acid-base reactions

Answer 36

the acid

Question 37

what is an acid

Answer 37

proton donor

Question 38

what is a base

Answer 38

proton acceptor

Question 39

write the acid-base step between Br and H2SO4

Answer 39

NaBr(s) + H2SO4(l) → NaHSO4(s) + HBr(g)

Question 40

write the redox step between Br and H2SO4

Answer 40

2 HBr + H2SO4 → Br2(g) + SO2(g) + 2 H2O(l)

Question 41

write the redox equations for Br and H2SO4

Answer 41

Ox ½ equation 2Br - → Br 2 + 2e- | Re ½ equation H2SO4 + 2 H+ + 2 e- → SO2 + 2 H2O

Question 42

what is the role of H2SO4 in the redox step

Answer 42

oxidising agent

Question 43

what observations for Br and H2SO4

Answer 43

HBr ; white steamy fumes Br2 ; orange fumes S02 ; odourless, acidic

Question 44

write the acid-base step between I and H2SO4

Answer 44

NaI(s) + H2SO4(l) → NaHSO4(s) + HI(g)

Question 45

write the redox stepS between I and H2SO4

Answer 45

2 HI + H2SO4 → I2(s) + SO2(g) + 2 H2O(l) 6 HI + H2SO4 → 3 I2 + S (s) + 4 H2O (l) 8 HI + H2SO4 → 4 I2(s) + H2S(g) + 4H20 (l)

Question 46

write the redox equations for I and H2SO4

Answer 46

Ox ½ equation 2I - → I2 + 2e- Re ½ equation H2SO4 + 2 H+ + 2 e- → SO2 + 2 H2O Re ½ equation H2SO4 + 6 H+ + 6 e- → S + 4 H2O Re ½ equation H2SO4 + 8 H+ + 8 e- → H2S + 4 H2O

Question 47

what observations for I and H2SO4

Answer 47

``` HI ; white steamy fumes I2 ; black solid/purple fumes S02 ; colourless, acidic gas S ; yellow solid H2S ; gas with bad egg smell ```

Question 48

write the reaction between Cl and water

Answer 48

Cl2(g) + H2O (l) ⇌ HClO (aq) + HCl (aq)

Question 49

write the reaction between Cl and water in sunlight

Answer 49

2Cl2 + 2H2O → 4H+ + 4Cl- + O

Question 50

what is chlorine in water used for

Answer 50

to kill bacteria, prevent reinfection + growth of algae

Question 51

write the reaction between Cl2 and cold dilute NaOH

Answer 51

Cl2(aq) + 2 NaOH (aq) → NaCl (aq) + NaClO (aq) + H2O (l)

Question 52

what is NaClO

Answer 52

sodium chlorate (I)

Question 53

what is NaClO3

Answer 53

sodium chlorate (V)

Question 54

what is K2So4

Answer 54

potassium sulfate(VI)

Question 55

what is K2SO3

Answer 55

potassium sulfate(IV)