Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

A Level > Chemistry paper 2 corrections > Flashcards

Chemistry paper 2 corrections Flashcards

1
Q

How does purity affect melting points?

A

Impure compounds have lower melting points

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Alcohol to haloalkane

A

NaCl and H2SO4

Forms product and NaHSO4 and H2O

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is an easy trick they can play when oxidising alcohols?

A

Tertiary alcohols dont oxidise

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the number on [O] when oxidising to aldehydes/ketones?

A

1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the number on [O] when oxidising to carboxylic acids?

A

2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What happens when HCl acid is added to molecules such as amino acids?

A

NH2 becomes NH3+Cl- salt

COOH is not affected

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What happens when NaOH alkali is added to molecules such as amino acids?

A

NH2 not affected
COOH becomes COO-Na+ salt
OH on phenols become O-NA+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Why are phenols more reactive than benzene?

A

OH partially delocalises into the pi system
The electron density increases
The phenol is more susceptible to an electrophilic attack

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How does the halogen affect the rate of reaction?

A

Iodine is less reactive, so has a weaker bond, so the reaction is faster
Chlorine is more reactive, so has a stronger bond, so the reaction is slower

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the correct wording when talking about E/Z isomers

A

Priority groups

Largest atomic number

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Test for an aldehyde

A

Tollens’ reagent

Silver mirror

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Test for carbonyls

A

2,4-DNP
Orange precipitate produced
Can use the melting points of the precipitate to determine to compound by comparing them to predetermined values

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

nitrile to amine

A

Reduction
LiALH4 and H2SO4
Or H2 and Ni catalyst (this is the same as for alkene to alkane)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

WHat is easy to forget when reducing aldehydes

A

The carbon on the C=O is easy to miss when it becomes an alcohol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Nitrile to a carboxylic acid

A

H2O, dilute HCL and reflux

Can sometimes be said to just be H+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How are major and miner products determined in electrophilic addition?

A

Less reactive atom attaches to the carbon with the most hydrogens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What happens when you add Na2CO3 to phenol?

A

COOH becomes COO-Na+

OH is not affected

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What affects boiling points?

A

Non polar molecules- London forces

Polar molecules- hydrogen bonding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Purification steps

A 
-Dissolve impure solid in MINIMUM volume of hot solvent
Cool solution
FIlter solid to remove impurities
Recrystalisation
Scratch with a glass rod
Wash with a cold solvent and dry
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is an addition reaction?

A

When two molecules become one

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Why do boiling points of simple covalent molecules increase down the group?

A

Because they’ve got more electrons

So they have more/stronger London forces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Why does reactivity down group 2 increase?

A

Because there is more electron shielding
Electrons are less attracted to the nucleus
Ionisation energy decreases
Less energy is needed to remove an electron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the charge on NO3?

A

-1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What counts as a H NMR environment which can often be missed?

A

The hydrogen on the OH group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What is the most acidic- amide, carboxylic acid, ester or acyl chloride?
Acyl chloride
26
Why does a branched compound have a lower boiling point to an unbranched compound?
Because there are less points of contact Less surface interaction Less London forces can form Less energy is needed to break the London forces
27
What is the definition of stereoisomers?
Molecules that have the same structural formula but a different arrangement in space
28
How does a molecule act as an electrophile?
It accepts a lone pair of electrons
29
Why is one of the products of electrophilic addition a major product?
Because the carbocation intermediate is more stable (the one with the + on it) when the hydrogen bonds to the carbon with the most hydrogens on it
30
How do you check the purity?
Melt in a capillary tube Find the melting point Compare to known values If it is a sharp melting point close to the known value, it is pure
31
How does an electron donating group work?
It donates a PAIR of electrons/LONE PAIR into the benzene ring or It is DELOCALISED into the benzene ring
32
When is a halogen carrier needed?
When it is a benzene or when there is an electron withdrawing group
33
What is the product when an amine reacts with an acid?
NH3+Cl-
34
What is the structure of a hydrogen bond?
The H on the H2O binds to the lone pair on the O on the molecule. Make sure the LONE PAIR is included
35
How do you name aromatic compounds?
Cyclo- | eg. 3-methylcyclohexanol
36
When talking about oxidation of alcohols to aldehydes, what should you write instead of heat?
Distillation
37
What is a property of cyclohexane?
It is weakly acidic
38
When asked to analyse H NMR what must you do?
Write out the information fully, describing where on the spectrum the peak is, whether it is a singlet etc. , how many hydrogens it has and what structure each peak represents eg. CH3
39
What is the bonding and shape of H2O
H2O has two bonded pairs and 2 lone pairs so it forms a tetrahedral structure shape which is nonlinear with 104.5 degrees
40
What can you work out from the amount of optical isomers there are?
The amount of chiral centres | eg. 4 optical isomers = two chiral centres
41
What happens when a carboxylic acid reacts with magnesium?
Magnesium is a group two metal so it will put brackets and 2 around the COO- part
42
What factors affect retention time?
Solubility- more soluble will spend more time dissolved in the stationary phase Boiling point- higher boiling point means it will spend longer condensed in the tube Temperature of gas chromatography equipment- hotter means more time evaporated
43
How does gas chromatography separate the compounds in the mixture?
Solubility
44
What is M+?
Molecular ion
45
What is easy to forget when reducing aldehydes?
The carbon that is already in the aldehyde
46
In electrophilic substitution of phenol, what are the products?
Hydrogen ions from the ring, which will join up with compounds like Br to make HBr
47
What is the difference between bonding in kekules structure and benzene?
P orbitals overlap in the double bond The pi bonds/electrons are localised in the double bond The pi bonds/electrons are delocalised in the pi system
48
What are the reagents for turning NH2 into N+?
HNO2
49
What is there to remember if NH2 is anywhere to be seen?
If acid is involved, it will change to NH3+!
50
What can amino acid type structures form if they dont form condensation polymers?
Rings | They can form them with just one monomer or two
51
What is a use for NMR spectroscopy in medicine?
Magnetic resonance imaging | Body scanners
52
What region of the electromagnetic spectrum is used in H NMR spectroscopy?
Radio waves
53
In electrophilic substitution, what can the electrophile be?
Br-Br
54
When converting nitrophenol (NO2) to aminophenol (NH2), what is the reaction?
Nitrophenol + 6[H] -----> aminophenol + 2H2O
55
How is an aminophenol (NH2) able to react with an acid?
The lone pair on the nitrogen can accept a proton
56
What is a condensation polymer?
WHere monomers are joined together and a small molecule is lost such as H2O
57
When talking about oxidation, what must you always say?
Orange to green colour change
58
What can molecules with functional groups on both ends do?
Form a ring
59
What does it mean when it says a peptide bond?
An amide bond, not an ester bond
60
In terms of isoelectric point, what can they get you to draw?
The zwitterion and an amino acid in an alkali or acidic state NH3+ or COO-
61
What are benefits of using single stereoisomers in the synthesis of drugs?
No side effects | Stops the need to separate out the stereoisomers (cost)
62
Whenever you see hydrolysis of ester/amide bonds, what must you do?
Look for whether it is acid or base hydrolysis Acid = NH3+ Base = COO-Na+
63
How can products be identified from gas chromatography and mass spectrometry?
Volatile compounds are separated | They are compared with a spectral database
64
Why is TMS used in NMR spectroscopy?
Because it is the standard | It is 0 ppm
65
When analysing H NMR, what should you do to show all your reasoning?
Make a table of all the information you know Connect each environment to the functional group part of the molecule Then add together the environments you know go together
66
What can cause an increase in risk of suffering from heart disease?
A trans unsaturated fatty acid | Increases the amount of bad cholesterol
67
When naming organic molecules of benzene rings, how do you know what number to give them?
1 is always on OH | Don't miss out on that 1 and make everything one less!
68
What is the process by which TLC separates amino acids?
Adsorption
69
What type of reaction is reduction of aldehydes?
Nucleophilic addition
70
How might a polyester be degraded?
Photodegradable Hydrolysis Biodegradable
71
In zwitterions, what happens if there are other NH3 groups on it?
It is still only the one COOH and NH3 that swap Hs
72
Why might zwitterions have different isoelectric points?
Because an amino acid has another NH3 group on it which will mean its isoelectric point is a higher pH/above 7
73
What should you look out for when counting chiral centres?
Centres with the same group on them eg two CH3 groups look like sticks in skeletal
74
What does it mean if it is a natural steroid?
It produces only one optical isomer
75
How can results from gas chromatography predict compounds and their relative proportions?
Measure retention times Compare them to a spectral database Calculate the are under the peaks for relative proportions
76
What explains the shape of molecules?
Bonding pairs repeleg. in tetrahedral, 4 bonding pairs repel
77
Why are cyclo/aliphatic compounds used in fuels?
Because they have more efficient burning
78
What are the termination steps in free radical substitution>
2Br to Br2 C6H11 + Br to C6H11Br C6H11 + C6H11 to C12H22
79
What is the small product of electrophilic addition with Br2?
HBr
80
How are esters named?
First part is the part that is after the O
81
How is CO2 stored?
By reacting with metal oxides (GROUP 2) | In the sea
82
What is the reaction in catalytic converters?
2NO + 2CO ----> 2CO2 + N2
83
What is the definition of structural isomers?
Same molecular formula but different structural formula
84
What are the products when making an ester?
Ester and H2O
85
What is it easy to forget when comparing things about different compounds?
To actually compare them!
86
Why is D used in NMR instead of H?
Doesn't absorb | Doesn't give a peak
87
Why are some artificial sweeteners not used any more?
Adverse side effects
88
What is the difference in enthalpy change of hydrogenation between Kekule's structure and benzene?
The enthalpy change of hydrogenation is less exothermic
89
What is meant by retention time?
The amount of time the compound takes to exit the column
90
What is the structure of a tryglyceride?
The three carbons, then the Os, then the C=O group
91
How can the problems of producing two optical isomers be overcome?
With bacteria With chiral synthesis By using natural chiral molecules
92
What is meant by an alpha amino acid?
Both the NH2 and the COOH are joined to the same carbon

A Level (25 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions