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A-level Chemistry <3 > 5- Rates, Equalibrium, PH, Energy, Transition Elements > Flashcards

5- Rates, Equalibrium, PH, Energy, Transition Elements Flashcards

1
Q

Oxidation is ….. of electrons

A

Loss

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2
Q

Reduction is …. Of electrons

A

Gain

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3
Q

What is a redox reaction

A

Reduction and oxidation happening simultaneously

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4
Q

What is an oxidising agent

A

Accepts electrons amd gets reduced

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5
Q

What is a reducing agent

A

Donates electrons and gets oxidised

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6
Q

What can be combined to make a full redox equation

A

An oxidation half equation can be combinded with a reduction half equation

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7
Q

What needs to be the same for half equations can be combined

A

The electrons

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8
Q

What are the only things your allowed to add to half equations

A

Electrons
H+
Water

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9
Q

What is the oxidation of iron, half equation
Fe2+ to Fe3+

A

Fe2+ —-> Fe3+ + e-

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10
Q

What is the reduction of manganateequation

A

MnO4- +8H+ +e- —> Mn2+ 4H2O

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11
Q

What elements are good at changing oxidation statex
And so therefore are good at what

A

Transition elements
This makes them usefull oxidising and reducing agents - as they readily give out and receive electrons

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12
Q

What colour is MnO4-

A

Purple

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13
Q

What is the colour change + why
Acidified potassium manganite (vll) redox

A

Purple to colourless
As the (Mn(H2O)4) 2+ Is colourless

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14
Q

What is the colour change + why
Acidified potassium dichromate redox

A

Orange
(Cr(h2o)6)3+ is violet (but usually looks green)
So a colour change looks orange to green

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15
Q

Tritations using transition element ions are what

A

Redox tritations

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16
Q

How to carry out a redox reaction
(Of manganite (vlll) ions)

A

first you measure out a quantity of the reducing agent eg.
aqueous Fe2+ ions, using a pipette, and put it in a conical flask

2 You then add some dilute sulfuric acid to the flask
- this is an excess, so you don’t have to be too exact.
(This acid is added to make sure there are plenty of H+ ions to allow the oxidising agent to be reduced)

  1. Now you gradually add the aqueous MnO4- (the oxidising agent) to the
    Reducing agent using a burette, swirling the conical flask as you do so.

You stop when the mixture in the flask just becomes tainted with the coloe
of the MnO4- and record the volume of the oxidising agent added

Run a few tritiations and then calculate the mean volume or MnO4-

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17
Q

T or f
In a redox tritiations
You add the known concentration to the substance of the unknown concentration

A

T

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18
Q

What can you do during a redox tritiations wot make the colour change Easier to spot

A

You could use a coloured reducing agent and a coloured oxidised agent - so you’d be looking for the moment the colour of the flask dissapears

Doing the reaction inffont of a white surface

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19
Q

Ensure you can do redox tritations calculations

A

👍

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20
Q

What is the definition of rate of reaction

A

The change in conc of reactants ( or products ) per unit time

21
Q

What are the units of rates of reaction

A

Mol dm -3 s -1

22
Q

What is activation energy

A

The minimum amount of energy a particle needs in order to react
The energy ( enthalpy) difference between the reactants and the transition state

23
Q

What does rate of reaction describe

A

How quickly reancys are used up or how quick products are formed

24
Q

What 2 diff rates can we look at when looking at rate of reaction;

A

The average rate for the entire reaction
Or
The rate at a specific point ( instantaneous rate )

25
Q

What 4 ways can you measure rate

A

Vol of gas given of
Changes in PH (Ph probe )
Colour change ( use of colorimeter)
Loss of mass ( gas given off in an open system )

26
Q

Make sure you know what the first, zero and second order graphs look like (6)

A

Check

27
Q

What are the observations for the iodine/thiosulfate tritiations

A

CuI precipitation ( white)
Iodine - brown solution

28
Q

What are the 3 main used of iodine / thiosulfate tritiations

A

Used to determine the clo- conctent in household bleach
Used to determine the cu2+ content in cu((ll) compound
Used to determine the cu content in copper alloy

29
Q

In iodine / thiosulfate tritations
What are the oxidising agents oxidiseing

A

I- to I2

30
Q

What is the iodine tritated against

A

Standard solution of sodium thiosulfate (S2O3 2- ion )

31
Q

SO2O3 2-
In iodo thiosulfate tritations half equation goes to

A

S4O6 2-

32
Q

What is the best way to balence the thiosulfate half equation

A

Look at charges not oxidation number

33
Q

What is the molar ratio ot thiosulfate ion to iodide

A

2 : 1

34
Q

What do you see in the iodine and thiosulfate tritations

A

Iodide -brown , fades to straw colour
When no iodine left colourless
( you can make this colour change easier to see by adding starch when it turns straw yellow)

35
Q

What is rate of reaction usually measured in terms of

A

How fast the conc of One of the reactants is falling

36
Q

T or f
Moles in the equation don’t effect the rate equation

A

T

37
Q

What is rate of reaction proportional to

A

The rhe concentration of a particular reactant raised to a power

38
Q

For each reactant in the rate equation
The power =

A

The order of reaction for that reactant

39
Q

What orders are there in the rate equation

A

Zero
First
Second

40
Q

How are orders determine in the rate equation

A

Experimentally

41
Q

What is the overall order

A

The sum of the individual orders of reacts in the rate equation

42
Q

Describe zero order

A

If the conc. changes, rate doesn’t change rate is proportional to [A]^0 = 1

43
Q

Describe first order

A

Conc double, rate will double
Rate is proportion to [A]^1

44
Q

Describe second order

A

Conc double, rate inc. by factor 2^2 = 4
Rate is proportional to [A]^2

45
Q

What is K in the rate equation

A

Rate constant for a reaction

46
Q

Is the rate constant differnt for differnt reactions

A

Yes

47
Q

What are the units for the rate constant

A

The units depend on the order of the reaction

48
Q

What is the value of the rate constant effected by

A

Temp
Presence / change of a catalyst

49
Q

What does the rate equation provide lots of info about

A

The mechanism for the reaction

A-level Chemistry <3 (9 decks)

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