Module 5 Last 2 Chaoters

Question 1

How to make standard half cell

How ti make it standard

Answer 1

1) metal strip
2) dipped into its ION solution

Made standard by RTP and 1mildm-3 (must label)

Question 2

How to make an ion / ion half cell (2)

Why do we need this extra thing

Answer 2

1) inert metal like platinum
2) dipped into solution of BOTH ions

At standard condtions

We need extra rod as it allows the electrons to move around in a circuit

Question 3

Standard electrode potential definition

Answer 3

The tendency to be REDUCED and gain electrons, measured against the standard conditions ( hydrogen cell + standard condition)

Question 4

So what is standard electrode potential of copper for example by defintiom

Answer 4

So thr standard potential of an element is thr emf of thr hslf cell when connected to a STANDARD HYDROGEN HALF CELL with everything in the standard conditions

Question 5

How is a standard hydrogen half cell made

Answer 5

1) container with H+ (aq) solution ar 1moldm-3
2) a PLATINUM INERT metal strip
3) like a cover over it connecting to a source which pumps H2 gas at 100KPA and 298k
4) then wire connecting to your voltmeter and other half cell

Question 6

Salt bridge, what’s it for and how js it made

Answer 6

• allows ions to flow
• concetrsted solution of an electrolyte that does not reavts with either solution

= typically filter paper soaked in aqueous KNO3

Question 7

If you are using an ion ion half cell, what does the cidntrstion of both have to be (choice)

Answer 7

Must be equimolar

Can do this by just setting them both to 1, but they can both by
E 2 for example no pornlem

Question 8

How to tell which metal or non metal more reactive using half cells

Answer 8

Metals lose electrons , so the hslf cell with greatest tendency to lose

This is the MOST NEGATIVE potential for most reactive for metal

Vice Verca for the non metal

Question 9

How to tell which electode is the positive electrode and which is the neagtive very quickly

(Using potentials)

Answer 9

More positve potential means it’s gaining electrons, thus had to be positive

More negative potential is the negative

Question 10

Biggest reducing agent / sliding using potentials?

Answer 10

Biggest reducing agent = biggest oxidising thing = so. Most negarive

Question 11

How to see what happens to a standard electrode potential if the concentration of an ion soltuon is higher or less than 1

Answer 11

Use le Chatellier to see the shift
- if electrons removed less negative, if added more negative

Naturally thisnwillm affect the e cell

Question 12

What are 3 LIMITATIONS TO USING STANDARD ELECTRODE POTENTIALS to predict e cell between two hslf cells?

Answer 12

1) does not take into account kinetics of the reaction, such as rate of reaction
2) might and typically never at standard conc 1 moles-3, which will change e cell as seen
3) not at standard condtions in general, which will affect e cell

Question 13

Primary fuel cells

How do they work?
What happens when chemicals are used up

Answer 13

Non rechsrbsle and designed to use once
- run with same technology as 2 half cells

2) as chemicals used up, the voltsge falls. Once flat, no use, so discarded

Question 14

Secondary cells

What technology

Answer 14

Are RECHARGABLE

1) here tje reaction producing energy can be reversed
2) eventually the amount this can happen to decreases

Question 15

MARKSCHEME Q

BENEFITS AND RISKS OF USING batteries like lithium (1 mark benefit 2 non)

Answer 15

1) can be made compact and thus used in small spaces for smaller devices

2) however very reactive, and have IGNITED IN THE PAST.
- some chemicals are toiz in batteries when it comes to Disposing them once have no more use

Question 16

What is a fuel cell

Key point

Answer 16

A fuel cell is a cell that produces voltage based on energy provided when fuel reavts with oxygen

Question 17

Features of a fuel cell (spec points ) , what happens at each electode?

Does a fuel cell need to be recharged?

Answer 17

1) the fuel and oxygen enter the fuel cell and the PRODUCTS LEAVE .
- the electrolyse stays put

2) a fuel does not need to be recharged at all. As long as fuel is out in , it can continously produce a voltage.
- this is a benefit compared to a secondary cell as time isn’t used in recharging

Question 18

Why is the most common fuel cell hydrogen?

Answer 18

This is because it’s by product I’d only WATEr, not toxic, other things could produce products which are lomg

Question 19

Two exceptions to electron config for d block

Answer 19

Copper and chromium , 3d5 and 3d10, as more stable

Question 20

TRANSITION ELEMENT DEFINITION

Answer 20

D block elements that form at least one ion with a PARTIALLY filled d orbital

Question 21

Explain why zinc and scandium aren’t transition

IMPORTSNT

Answer 21

Check their electron configurations
- scandium only produced +3 ions. Therefore no ions are partially fill with d orbital
- zinc only forms 2+ ions , so as 4s lost first agsin no orbital d is partially full

Everything else the ion they form is with a partially full d orbital

Question 22

Again what is thr use of catalysts , and risk , and overall conclusion

Answer 22

• can reduce energy needed in chem process, and thus fossil fuels and emissions given off
• some calaysts are toxic and this is found in the transition metal

But overall benefit outweighs the risk of making the catalyst so still used

Question 23

What is a complex ion

Ligand

Coordinate number

Answer 23

Complex ion : when one or more molecule / ion (ligand) is attached to a central metal ion

Ligand = a molecule/ ion that donates a pair of electrons to a central metal ion , forming a coordinate bond

Coordinate bond =a covalent bind where both of the shared pair of electrons came from one atom

Coordinate number =the number of coordinate bonds in the complex ion

Question 24

How much charge does oxalate bidenatet ligand change

Answer 24

-2 , don’t forget

Question 25

What shape will anythign with chlorine ions make and why compared to like water

Answer 25

Chloride ions are big
- thus the max a central ion can hold is 4
- therefore tetrahedral
- whereas ammonia water etc can be 6

(Remember chlorine will reduce the charge too)

Question 26

When are sqaure planar shapes made

What’s the binding degree for square planar ?

Answer 26

When the central metal ion is palladium, platinum or gold , then there will always be 4 ligands, and it’s a SAAURE PLANAR SHAPE

This is 2 wedge and 2 dashed line

2) 90°

Question 27

How can cis trans isomerism be shown in sqaure planar and octahedral

Answer 27

There must be 2 groups which are the same only else it won’t work

1) for square planar if advanced then did , if oppsite then trans. 90 and 180 angles
2) in octahedral if advent again dis, and if COMPLETELY OPPSITE then trans . Remember has to be 2 groups same

(Works for bidentate in its too)

Question 28

Optical isomerism in octahedral

What’s the condition

Answer 28

Must be 2 or more bidentate ligands else it can’t show

Remember optical isomers are non super impossible mirror images of each other , and so when reflect can impose

Question 29

What is cis platin used for ( SPEC POINT )

How does it work

Answer 29

1) used for cancer treatment
2) binds to DNA of tumour cells and forms a platin complex, which prevents cell division

Question 30

What is the benefits and risk of using cis platin

SPEC POINT (2 MARKS )

Answer 30

Benefit is it can help stop the tumour from dividing and getting bigger

The Risk it can produce unpleasant side effects

Therefor alternative is trying to be found, but still used