# (WCH14) IAL Chemistry Unit 4- 8 January 2021 (Exam Discussion)

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65-69 (10)
22.22%
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#1
This is my first exam of the January session. I think it is a good idea to start the thread early so we can talk about our preparation for the exam throughout Christmas!
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#2
I am going to help you all with a Unit 4 album. The tracks include:
11A. 1-3 (parody of Warriors)
12A (parody of Blame it on my youth)
12B (parody of I Have A Dream)
13A.1 (parody of Blinding Lights)
13A.4 (parody of Walking on the sun)
14A (parody of Take Me Home Country Roads)
14B (parody of Loch Lomond)
15B (parody of Roar)
15C (parody of 血淚的磨練)
15D (parody of Try Everything)
15E.5-8 (parody of I want it that way)
Last edited by 8013; 3 weeks ago
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#3
There you go for tracks 1-5! Be sure to sing them once every day!
Topic 11A.1-3:
Reaction Orders (Original: Imagine Dragons-Warriors) (2015)
V1. A rate equation's expression to show relationship
Between the rate and reactant's concentration, it has its own power
The unit of it depends on order of reaction
The powers will go up from zero to third order
Chorus: Here it is, don't turn away now
This is the equation that describes rate
Here it is, don't turn away now
This is the equation that describes rate orders
V2. More than one (reactant), the orders will add up
Get an overall order, and it never dies
Concentration doubles, first (order), rate doubles
Second, it's fourfold
Zero, it stays same, the rate of reaction
(Repeat Chorus x2)

Topic 12A:
Entropy Song (Original: Blink 182- Blame It On My Youth) (2019)
V1. A reaction happens itself, without any kind of external help
Is a spontaneous one, like burning of magnesium in air
Besides the enthalpy change, the entropy is a driving force too
It’s a matter property, and bumps up total entropy
From Second Law, can you absorb it now
Chorus: Add up that of the system, and that of the surroundings,
Spontaneous positive, thermodynamically stable
At a higher temperature, and with more particles
And more complex substance, entropy will go up
V2. Add up the product entropies, then subtract that of the reactants
No matter any state, you get the system entropy change
Flip the sign of the enthalpy, divide by temp, for the surroundings
That means exothermic, this value is always positive
Total up, can you absorb it now
Bridge: Reaction with high Ea, negative entropy, kinetically stable
And some heat energy will bring the entropy value up
And more moles to the right

Topic 12B: Lattice enthalpy song (I Have A Dream parody) (1979)
Standard lattice energy change
When one mole of gaseous ions
Forms ionic compound at 2 9 8 K
And 100 KPa, standard conditions
Add given enthalpies, use Hess Law in Born Haber Cycle
Then we can get the experimental lattice energy
But there’s one more, theoretical
By principles of electrostatics
A large difference, more covalent
Small charged cations have large polarising power
Anion with high charge and a larger size
Will have same effect too, more polarising
Solution enthalpy, when a mole of ionic solid
Dissolves in H2O, forms infinitely dilute solution
Dilution effect affects value
1 mole hydrated by H2O
Ion dipole, it’s hydration
It’s always negative, more with higher charge
Stronger interaction, decrease down a group
Lattice plus solution, by the Born Haber cycle
Equates the enthalpy change of hydration of the ions
It’s enthalpy in a lattice (x2)

Topic 13A.1:
Equilibrium KC (Original: The Weekend-Blinding Lights) (2019)
V1. In homogenous, when reactants and products in same phase
When they divide from each other, it’s a constant
It does not change, in any concentration unlike position
Just one thing affects its value, temperature
First we have to find concentrations
Number of moles over volume
Determine in experimentation
Chorus: I said, ooh, ooh, it’s equilibrium
When products and reactants are constant
*I said, ooh, ooh, it’s the KC constant
The constant determined by concentration
V2. Use the mole ratio, subtract from initial concentration
Then you take the powers in each side
Multiply all the powers, both the values and units
Then divide to find the KC constant
(Repeat Chorus)
For heterogeneous reactions, as solids use density, don’t take in
Take liquid and gas in required temp
(Repeat *x2)

Topic 13A.4:
Factors Affecting Equilibrium (Smash Mouth- Walking On The Sun) (1999)
V1. Larger constant means product more concentrated
Which means position is closer to product side
There are four factors which affect the equilibrium position
But only temperature affects its KC or Kp constant
Exothermic high temp, the constant will be bumped down
Endothermic high temp, the constant will be risen
The higher temperature, no matter enthalpy change
Will shift the position in endothermic direction
chorus: The change in position can be shown by its constant
Temperature and pressure, concentration, catalyst
Only in temperature, KP or KC will change
And all of these affect the position of equilibrium
V2. Change in pressure changes position, not constant
When it goes up, QP down, must shift to right
You can add reactant, same as change in concentration
Or change system’s volume or add noble gas
Volume higher, both sides lower concentration
But this will cause position to shift to the left
Noble gas unreactive, so it has no effect
Moles and pressure constant, KC, KP remain the same
V3. Concentration change, just position follows
As one component alters, the QC is different
Composition must change for QC be back to KC
For mixture to reach equilibrium again
Catalyst does not change constant or position
But it makes rate faster, faster equilibrium
Ratio and concentration of products both are constant
As it does not have chemical change when reacting
Last edited by 8013; 4 weeks ago
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#4
Here are tracks 6-7 for topic 14. After getting through a lot of upbeat songs, why not move to older, slow paced songs for the next topic?
(14A) Acid base song (John Denver- Take Me Home Country Roads) (1971)
V1. Minus log H+ is pH, the H+ is concentration
Stronger acid dissociates more completely in water
Chorus: Acid donates proton to its conjugate base
A base accepts single proton from conjugate acid
V2. Ka’s dissociation constant, constant at just one temperature
pKa equals to log Ka, smaller more acidic, (reverse for Ka) (This means larger Ka is more acidic)
V3. Kw, ionic product of water, H+ and OH concen(tration) product
And to find Ka or Kw, x square equals base concentration

(14B) Buffer solution song (Ella Roberts- Loch Lomond) (1841)
V1. The pH falls slow, and then it drops fast
When equivalence point is finally reached
This point can be deduced by an indicator
Which changes colour at a pH close to its value.
Chorus: In pH curve when pH falls smallest amount
Large concentration both acid, conjugate base
Removes excess solution by dissociation when
Small volume of acid, base added, it’s buffer
V2. When you need to find the pH of buffer
Find molarities by molar mass or volume
H+ is Ka times acid divided by salt
Use pH formula to find this buffer pH
V3. Or use total volume and molarity
To work out concentration of acid and salt
pKa plus log acid by salt, you get the pH
This is the Henderson-Hasselbach equation
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#5
Then we have the last four tracks!
(15B) Carbonyl Compounds (Katy Perry- Roar) (2013)
V1. Aldehydes have RCHO
And ketones have RCOR
With C=O double, they are carbonyl
They all have distinctive smells
Larger ones have more plesant ones
They are soluble, form H-bonds with water
They have polar group, dipole-dipole, and have London forces too
When mass greater, harder to boil, cause more London forces
Harder to dissolve in longer chains, hydrocarbon significant
Just aldehydes can oxidise
Chorus: Add Fehling's it turns from blue to red, 2-plus to 1-plus
And silver mirror forms with Tollen's reagent
Ethanal and methyl ketones form CHI3
2,4 Dimethyl hydrazine, named Brady's reagent (tur-ur-ur-urns orange x3)
From a green colour
V2. Add KCN and HCN, nitriles are the product formed
As groups to C=O are planar, CN attacks either side
Despite a chiral centre here, a racemic mixture is formed
Both can reduce to alcohols with LiAlH4
The solvent is some dry ether

(15C) Carboxylic acids (Airport Strikers theme song) (2020)
Carboxylic acids have a COOH group
It has a C=O functional group and OH acid group
It allows H bonds to form between each other
It has much higher melting boiling points
H bonds with water shows it’s soluble
A reducing agent of LiAlH4
Provides H minus nucleophile, in a dry ether solvent
It’s immediately reduced to primary alcohols
Aldehydes can’t be isolated as they’re more reactive than acids
Carboxylic acids are a weak acid
And as it has a covalent nature, it reacts with a base
To produce ionic salt, in neutralisation
It is a type of carboxylic salt, formula is RCOO-
When OH replaced by Cl, it’s COCl
Must be anhydrous as both sides can react with water
Vigorous means there’s no heat, POCl3 must distill in a fraction
When it reacts with alcohols in H2SO4
An ester forms in reaction, it’s slow, reversible
Acid can be prepared by oxidation of alcohols or aldehydes
Or by hydrolysis of nitriles when the CN bond is broken
It needs dry ether in an acidic hydrolysis
Plus 1 H plus, two H2O, ammonium’s also here (direct form!)
In alkaline (hydrolysis) add an OH and also a H2O
Carboxylate ion’s formed, plus H+ it turns to carboxylic acid

NMR spectra (I Want It That Way) (1999)
13C spectra
The vertical lines
Number of (chemical) environments
And chemical shift
The peaks show ratio between
These (chemical) environments
Check the table
And find shifts that way

There are two types of NMR spectra
13C and 1H to find structures
They can find chemical environments
With peaks in that way

With nuclear magnets
Forms chemical shift
Odd number isotopes
Detect in that way

There are two types of NMR spectra
13C and 1H to find structures
They can find chemical environments
With peaks in that way

The other type’s 1H or just proton
But with peaks by 1H atoms
The numbers are ratios
Of (hydrogen) environments
Or the number of protons

By n plus 1 rule
The peak will split up
It splits (x4)

Find protons next to C
Which have H bonded
Use tables to find the bonds
Compare areas, split patterns
We find it that way

There are two types of NMR spectra
13C and 1H to find structures
They can find chemical environments
With peaks in that way
There are two types of NMR spectra
13C and 1H to find structures
They can find chemical environments
With peaks in that way
Last edited by 8013; 3 weeks ago
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#6
I got 80/90 in the October 2020 paper. What grade is it?
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3 weeks ago
#7
(Original post by 8013)
I got 80/90 in the October 2020 paper. What grade is it?
Could you pm me the paper (qp and ms?) My teacher's ghosted us and we have no resouces as of now (
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#8
If I get below 72/90 in the specimen paper, due to a 1-0 defeat to Southampton FC, I will be singing this chant on screen as a forfeit:
https://www.fanchants.com/football-s...outhampton-fc/
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2 weeks ago
#9
(Original post by 8013)
I got 80/90 in the October 2020 paper. What grade is it?
Anyone chance of you pm me the paper? Thanks in advance
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2 weeks ago
#10
Guys any predictions as to what might be in the exam? Im stressing out too much and I literally have no clue what might be in. Have ur teachers made any predictions or anything?
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#11
(Original post by Sotiriendjw)
Guys any predictions as to what might be in the exam? Im stressing out too much and I literally have no clue what might be in. Have ur teachers made any predictions or anything?
My bet is on carbonyl compounds and Kc constant for Section B/C. These topics were not on Oct 2020 paper so they are likely to come up this time.
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#12
After you finished the exam tomorrow, remember to vote in the poll for your expected mark!
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2 weeks ago
#13
Good luck everyone, I'm having the exam within 2 hours.
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#14
It is 7°C down here. 🥶🥶🥶🥶
And it will get colder into the evening. I am taking the exam in the evening.
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#15
(Original post by BurningArsonist)
Good luck everyone, I'm having the exam within 2 hours.
What?
I am having mine at 530pm local time. That is longer than 3 hours!
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2 weeks ago
#16
It's 10:11 AM for me (+4 GMT) and it will start near 12:15 PM
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#17
(Original post by BurningArsonist)
It's 10:11 AM for me (+4 GMT) and it will start near 12:15 PM
For me it is 2:12 PM now. I start at 5:30 PM (so I start an hour behind you)
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2 weeks ago
#18
Good luck, though. Hopefully, everything goes well
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#19
I feel that the buffer question was quite difficult. I got 1.62, as hso4- is in excess and it should be more acidic.
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2 weeks ago
#20
(Original post by 8013)
I feel that the buffer question was quite difficult. I got 1.62, as hso4- is in excess and it should be more acidic.
I got the same!!
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