Module 5 Last 2 Chaoters Flashcards
How to make standard half cell
How ti make it standard
1) metal strip
2) dipped into its ION solution
Made standard by RTP and 1mildm-3 (must label)
How to make an ion / ion half cell (2)
Why do we need this extra thing
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
Standard electrode potential definition
The tendency to be REDUCED and gain electrons, measured against the standard conditions ( hydrogen cell + standard condition)
So what is standard electrode potential of copper for example by defintiom
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
How is a standard hydrogen half cell made
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
Salt bridge, what’s it for and how js it made
- allows ions to flow
- concetrsted solution of an electrolyte that does not reavts with either solution
= typically filter paper soaked in aqueous KNO3
If you are using an ion ion half cell, what does the cidntrstion of both have to be (choice)
Must be equimolar
Can do this by just setting them both to 1, but they can both by
E 2 for example no pornlem
How to tell which metal or non metal more reactive using half cells
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
How to tell which electode is the positive electrode and which is the neagtive very quickly
(Using potentials)
More positve potential means it’s gaining electrons, thus had to be positive
More negative potential is the negative
Biggest reducing agent / sliding using potentials?
Biggest reducing agent = biggest oxidising thing = so. Most negarive
How to see what happens to a standard electrode potential if the concentration of an ion soltuon is higher or less than 1
Use le Chatellier to see the shift
- if electrons removed less negative, if added more negative
Naturally thisnwillm affect the e cell
What are 3 LIMITATIONS TO USING STANDARD ELECTRODE POTENTIALS to predict e cell between two hslf cells?
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
Primary fuel cells
How do they work?
What happens when chemicals are used up
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
Secondary cells
What technology
Are RECHARGABLE
1) here tje reaction producing energy can be reversed
2) eventually the amount this can happen to decreases
MARKSCHEME Q
BENEFITS AND RISKS OF USING batteries like lithium (1 mark benefit 2 non)
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
What is a fuel cell
Key point
A fuel cell is a cell that produces voltage based on energy provided when fuel reavts with oxygen
Features of a fuel cell (spec points ) , what happens at each electode?
Does a fuel cell need to be recharged?
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
Why is the most common fuel cell hydrogen?
This is because it’s by product I’d only WATEr, not toxic, other things could produce products which are lomg
Two exceptions to electron config for d block
Copper and chromium , 3d5 and 3d10, as more stable
TRANSITION ELEMENT DEFINITION
D block elements that form at least one ion with a PARTIALLY filled d orbital
Explain why zinc and scandium aren’t transition
IMPORTSNT
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
Again what is thr use of catalysts , and risk , and overall conclusion
- 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
What is a complex ion
Ligand
Coordinate number
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
How much charge does oxalate bidenatet ligand change
-2 , don’t forget
What shape will anythign with chlorine ions make and why compared to like water
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)
When are sqaure planar shapes made
What’s the binding degree for square planar ?
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°
How can cis trans isomerism be shown in sqaure planar and octahedral
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)
Optical isomerism in octahedral
What’s the condition
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
What is cis platin used for ( SPEC POINT )
How does it work
1) used for cancer treatment
2) binds to DNA of tumour cells and forms a platin complex, which prevents cell division
What is the benefits and risk of using cis platin
SPEC POINT (2 MARKS )
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
