Elements of the sea Flashcards

1
Q

at the cathode the molecule…

A

accepts electrons

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2
Q

at the anode the molecule…

A

loses its electrons

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3
Q

chlorine can displace ____ and ____ because it is…

A

bromine and iodine
more reactive

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4
Q

what is the equation for chlorine displacing bromine?

A

2Br- (aq) + Cl2(aq) —> Br2(g) + 2Cl-(aq)

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5
Q

what is the equation for chlorine displacing iodine ?

A

2I- (aq) + Cl2(aq) —> I2(aq) + 2Cl-(aq)

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6
Q

what is brine

A

a solution of water with a high concentration of salts

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7
Q

all uncombined elements have an oxidation number of…

A

zero

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8
Q

the oxidation number of a monatomic ion is…

A

the same as it’s charge

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9
Q

for a neutral compound the overall oxidation state is…

A

zero

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10
Q

roman numerals tells you…

A

the oxidation state

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11
Q

the oxidation will _______________ for every election gained

A

decrease by one

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12
Q

the oxidation state will _____________ for every election lost

A

increase by one

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13
Q

reducing agents are…

A

oxidised

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14
Q

oxidising agents are…

A

reduced

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15
Q

what type of titration is used for finding the concentration of an oxidising agent?

A

iodine-sodium thiosulfate

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16
Q

what is the equation for when in the ions in iodine-sodium thiosulfate titration react?

A

I2 (aq) + 2S2O3^2- (aq) —> 2I- + S4O6^2- (aq)

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17
Q

what is the original equation for the sodium-iodine thiosulfate titration?

A

IO3 - + 5I- + 6H+ —> 3I2 + 3H2O

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18
Q

halogens get less reactive…
because..

A

down the group
as you go down the group atoms get larger so outer electrons are more shielded and having greater atomic radius making is harder to attract electrons to form an ion

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19
Q

halogens can displace..,

A

halide ions from solution

20
Q

chlorine will displace ….

A

bromide and iodine

21
Q

bromine will displace….
but not…

A

iodine
chlorine

22
Q

iodine won’t displace…

A

bromine or chlorine

23
Q

if bromide is displaced and formed you will see…

A

a colour change to orange

24
Q

if iodine is displaced and formed you will see…

A

a colour change to brown

25
Q

hydrogen halides contain

A

a halogen + a hydrogen

26
Q

why are hydrogen chloride and hydrogen fluoride stable when heated?

A

they a large molecules meaning the bonding electrons are further from the nucleus and shielded more by inner electrons

27
Q

are hydrogen halides acidic?

A

yes

28
Q

do hydrogen halides react with ammonia?

A

yes

29
Q

give the equation for the reaction between ammonia and hydrogen fluoride

A

HF (aq) + NH3 (aq) —> NH4F (aq)

30
Q

do hydrogen fluoride and hydrogen chloride react with sulphuric acid?

A

no

31
Q

do hydrogen bromide and hydrogen iodide react with sulphuric acid?

A

yes

32
Q

silver ions react with halide ions to form….

A

a precipitate

33
Q

when Ag+ is added to Cl- ions what is formed?

A

white ppt

34
Q

when Ag+ is added to Br- ions what is formed?

A

cream ppt

35
Q

when Ag+ is added to I- ions what is formed?

A

yellow ppt

36
Q

when ammonia is added to AgI what is seen?

A

ppt doesn’t dissolve

37
Q

AgCl ppt dissolves when _____ ammonia is added

A

dilute

38
Q

AgBr ppt dissolves when _____ ammonia is added

A

concentrated

39
Q

why is chlorine useful?

A
  1. used in water treatment
  2. kills bacteria
  3. used to make bleach
40
Q

%atom economy=

A

(Mr of desired product / sum of Mr of all products) x 100%

41
Q

the equilibrium constant is…

A

Kc

42
Q

dynamic equilibrium happens in a…

A

closed system

43
Q

what is the effect of increasing temperature at equilibrium?

A

shifts in the endothermic direction to absorb the heat

44
Q

what is the effect of decreasing temperature at equilibrium?

A

shifts in the exothermic direction to try to replace the heat

45
Q

what is the effect of increasing pressure at equilibrium?

A

shifts equilibrium to the side with the fewest gas molecules, reducing the pressure

46
Q

what is the effect of decreasing pressure at equilibrium?

A

shifts equilibrium to the side with the most gas molecules, increasing the pressure