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Chemistry - AS Level > ES Flashcards > Flashcards

ES Flashcards

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1
Q

Equation for atom economy

A

(Mr of desired products / Mr of reactants) x 100

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2
Q

Which blocks are these?

A
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3
Q

What is the charge of a group 7 element?

A

1-

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4
Q

What is disproportionation?

A

When a species is simultaneously reduced and oxidized to give two different products

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5
Q

What does oxidation mean?

A

.Gain of oxygen
.Loss of electrons
.An increase in oxidation number

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6
Q

What does reduction mean?

A

Loss of oxygen
Gain of electrons
Decrease in oxidation number

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7
Q

Half equation for reduction

A

Cl2 + 2e- —> 2Cl-

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8
Q

Half equation for oxidation

A

2Br- -> Br2 + 2e-

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9
Q

What is the oxidation state for an atom in an element? Eg. O2, Mg, Cl2

A

0

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10
Q

How do you work out the oxidation states of the elements in a compound?

A

Oxidation states of all the elements must add up to 0 if the compound has no overall charge
- Some elements have oxidation states which never change

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11
Q

Oxidation state of flourine

A

-1

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12
Q

Oxidation state of oxygen in a compound

A

-2 (except when combined with F)

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13
Q

Oxidation state of chlorine in a compound

A

-1 (except when combined with O or F)

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14
Q

Oxidation state of bromine in a compound

A

-1 (except when combined with Cl, O or F)

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15
Q

Which element will retain its oxidation state in a compound?

A

The more reactive element

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16
Q

What is the oxidation state of iodine in a compound?

A

-1 (except when reacted with F, O, Cl, Br)

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17
Q

What is the oxidation state of hydrogen in a compound?

A

+1 (except in a metal hydride eg, NaH)

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18
Q

What is the oxidation state of a group one element in a compound?

A

+1

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19
Q

What is the oxidation state of a group 2 element in a compound?

A

+2

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20
Q

What is the oxidation state of a group 3 element in a compound?

A

+3

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21
Q

What do the oxidation states add up to in PO4 3-?

A

-3

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22
Q

How to work out systematic names

A

1) identify the name of the compound
2) work out the variable the element which has a variable oxidation state
3) work out its oxidation state
4) place the oxidation number in Roman numerals next to the variable element

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23
Q

Oxidation state on 2I-

A

Still -1

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24
Q

What does a decrease in oxidation state mean?

A

REDUCED

25
Q

How to name an oxyanion

A

Place the oxidation number in Roman numerals in brackets after the -ate

26
Q

What is electrolysis?

A

The decomposition of a molten or aqueous ionic compound by passing an electric current through it

27
Q

What are the 2 electrodes?

A

Cathode - negative
Anode - positive

28
Q

What happens to cations and anions during electrolysis?

A

Cations (positive ions) are reduced at the cathode
Anions (negative ions) are oxidised at the anode

29
Q

When will hydrogen gas pass at the cathode?

A

If the solution is acidic
OR
If a group 1 or 2 or aluminium metal is at the cathpde

30
Q

Equation at the cathode if the solution is acidic

A

2H+ (aq) + 2e- -> H2 (g)

31
Q

Equation at the cathode if the solution contains a group 1, 2 or aluminium metal

A

2H2O(l) + 2e- -> 2OH-(aq) + H2(g)

32
Q

What happens if a less reactive metal (not group 1 or 2) is at the cathode?

A

Metal atoms are formed
Metal ion (aq) + electrons -> metal atom (s)

33
Q

What happens to when the anode and metal solution are the same?

A

Metal anode loses mass as metal atoms change to ions and go into the solution

34
Q

What happens to sulfates and nitrates at the anode?

A

Oxidized less easily than water so oxygen gas is produced at the anode
2H2O -> O2 + 4H+ + 4e-

35
Q

What happens to halide ions at the anode?

A

HAlogen is produced at the anode as they are oxidized more easily than water
2Cl- -> Cl2 + 2e-

36
Q

what are the colours and states of the halogens room temp and pressure?

A

Flourine - Pale yellow gas
Chlorine - Pale green gas
Bromine - red/brown liquid
Iodine - dark grey solid

37
Q

What happens to volatility down the group of halogens?

A

Increases

38
Q

What colours are chlorine, bromine and iodine in aqueous state?

A

Chlorine - green
Bromine - Orange
Iodine - Brown

39
Q

Why are halogens more soluble in organic solvents than water?

A

Because halogens are non-polar molecules so they’re more soluble in non-polar solvents

40
Q

Why does reactivity decreases down group 7?

A

Atomic radius increases
Shielding increases
Positive attraction of the nucleus is weakened
Harder to gain an electron for bonding

41
Q

What happens to oxidising power down the group?

A

Decreases
Ability to attract electrons decreases
As greater atomic radius
So more shielding

42
Q

when will a halogen displace a halide from a solution?

A

If the halide ion is below it on the periodic table

43
Q

Chlorine + bromide color change

A

Colorless -> orange

44
Q

chlorine + iodide color change

A

Colorless -> brown

45
Q

Bromine + iodide color change

A

Orange -> brown

46
Q

What is formed when chloride, bromid and iodide ions react with silver nitrate?

A

Cl- = white precipitate (AgCl)
Br- = cream precipitate
I- = yellow precipitate

47
Q

What happens when chlorine, bromide and iodide ions react with ammonia?

A

I- nothing
Br- dissolves in concentrated ammonia
Cl- dissolves in dilute ammonia

48
Q

Halide ion + concentrated sulfuric acid ->

A

Hydrogen halide + sulfate salt

49
Q

What happens to thermal stability down group 7?

A

HF and HCl are very thermally stable so will not split when heated
HBr will split when heated
HI will split more easily

50
Q

Why does thermal stability decrease down group 7?

A

Covalent bonds are weaker
As halogen atoms are larger
So bonding pair is further from nucleus
So they can be broken more easily

51
Q

Where do dynamic equilibriums occur?

A

In closed systems

52
Q

What happens to equilibrium if you increase temp?

A

Will shift to favor the endothermic reaction as heat needs to be lost

53
Q

What happens to equilibrium if you decrease temp?

A

Will shift to favor the exothermic reaction as heat needs to be gained

54
Q

What happens to equilibrium if you increase pressure?

A

Shift to the side with fewer molecules

55
Q

What happens to equilibrium if you decrease pressure?

A

Will shift to the side with more molecules

56
Q

What happens to equilibrium if you increase concentration?

A

Forward reaction will be favored
Increases yield of products on the right hand side

57
Q

What happens to equilibrium if you decrease concentration?

A

Reverse reaction will be favored
Increases yield of reactants on the left hand side

58
Q

Equation for equilibrium constant

A

Chemistry - AS Level (39 decks)

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