Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Chemistry > notes to learn for exam > Flashcards

notes to learn for exam Flashcards

1
Q

Describe the bonding and structure of benzene

A

P-orbitals overlap sideways above and below the ring which forms pi bonds.
Electrons are delocalised
C-C bonds are equal in length.

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

Compare the reactivity of benzene to phenol

A

Benzene has delocalised electrons
Benzene has low electron density so does not attract electrophiles
A lone pair from the O in phenol is delocalised into the ring so electron density is increased, so electrophiles are attracted more.
The ring in phenol is activated because of this.

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

What is meant by delocalised electrons

A

Electrons spread over more than two atoms

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

What uses nucleophilic additions?

A

Conversion of aldehyde/ketone to alcohol using NaBH4. H is the nucleophile
Conversion of aldehyde/ketone to hydroxnitrile using HCN. CN is the nucleophile

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

What is a nucleophile

A

An electron pair donor

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

What is an electrophile

A

An electron pair acceptor

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

What is an electron withdrawing group?

A

NO2, substitutes in 3+5 position. Decreases reactivity

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

What is an electron donating group?

A

NH2, OH, substitutes in 2,4,6 position.
Reactivty increases

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

What are the features of phenol?

A

C6H5OH
Aromatic alcohol
It is a weak acid, reacts with strong bases but not weak bases like carbonates.

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

Why can phenol react with bromine in electrophilic subsitution without a catalyst?

A

Bc the lone pair of electrons is partially depolarised into the benzne ring, this increases electron density and therefore phenol is more susceptible to electrophilic attack.
Br is more easliy polarised

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

Can phenol react with NO2-

A

Yes it can, it doesnt need a catalyst either.
Produces 2-nitrophenol and 4-nitrophenol.
The NO2- group is electron withdrawing so reactivity decreases.

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

What does fredel-craft acylation produce?

A

A phenolketone via electrophilic substitution

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

Explain how a student could determine the activation energy, for s reaction graphically using k and T

A

Plot a graph using lnk and 1/T
Find the gradient using change in y/change in x
Work out the activation energy by (-)R x gradient

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

How do you calibrate a ph meter?

A

place bulb of ph meter into distilled water and allow reading to settle, adjust it so it reads Ph7. The do the same with a standard solution of ph4 and ph10

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

What indicators are used for acid base titrations?

A

phenolphalein and methyl orange

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

What is the colour change of phenolphalein in acid base titrations?

A

Colourless in low ph, pink in high ph

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

What is the colour change of methyl orange in acid base titrations?

A

low ph red, high ph yellow

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

What indicator to use with strong acid and strong base?

A

phenolphalein or methyl orange

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

What indicator to use for strong acid weak base?

A

methyl orange

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what indicator to use for weak acid strong base?

A

phenolphalein

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

what indicator to use with weak acid weak base?

A

no indicator will work

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

what are optical isomers?

A

non superimposable mirror images

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

Describe the similarities and differences between the bonding in the kekule model and delocalised model of benzene

A

p-orbitals overlap sideways above and below the ring which forms pi bonds delocalised model has delocalised electrons
kekule model has localised electrons
kekule model has x3 alternating pi bonds

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

Describe two pieces of evidence to support the delocalised model of benzene

A

benzene is less reactive than alkenes, this is shown by bromine test not working on benzene so shows the bonds cannot be unsaturated.
The bond lengths in benzene are all the same length

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Why is NO2 an electron withdrawing group?

A

It has no orbitals that can overlap with the delocalised ring, it is also electronegative so it withdraws electron density from the ring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Why would an acid catalyst be needed in electrophilic substitution?

A

Attacking species isnt a strong enough electrophile
The carbon isnt strong enough to depolarise the attacking species

27
Q

What is an aromatic ring?

A

Has a benzene ring

28
Q

What does phenol react with, what does it form and what will it not react with?

A

Phenol reacts with strong bases like NaOH, it will form a salt
Phenol does not react with weak bases like carbonates because it is a very weak acid

29
Q

Can carboxylic acids react with carbonates?

A

Yes because they are a stronger weak acid

30
Q

What is esterification?

A

The reaction of a carboxylic acid with an alcohol, it is reversible.

31
Q

What would ethanoic acid and methanol form?

A

methyl ethanoate and water
a product of esterification

32
Q

What is the functional group of an ester?

A

-COOR
R could be another carbon, alkyl group etc

33
Q

What does the hydrolysis of an ester produce in the presence of an acid?

A

A carboxylic acid and an alcohol

34
Q

What does the hydrolysis of an ester produce in the presence of a carboxylic acid?

A

A carboxylic acid salt and an alcohol

35
Q

What is the functional group of an acyl group?

A

-RCO

36
Q

Are carbonyl compounds polar?

A

Yes, because there is a difference in electronegativity.
The C is positive and the O is negative

37
Q

What is the functional group of a primary amine

A

NH2

38
Q

What is aliphatic?

A

Straight chain, branched chain or non-aromatic rings

39
Q

What is a primary amine directly attached to a benzene ring called?

A

Phenylamine, is it aromatic bc it has a benzene ring

40
Q

Name some features of amines

A

Can do hydrogen bonding
soluble in organic solvents

41
Q

Why are amines basic?

A

The lone pair on the nitrogen in NH2 makes amines basic/they are a base

42
Q

What happens when an amine reacts with acid?

A

It forms a salt but doesn’t produce any water.

43
Q

Why are alcohols liquid at room temp but alkanes are gases?

A

Alcohol has hydrogen bonding which are stronger than the van der waal forces in alkanes so more energy is needed to break them

44
Q

What is meant by covalent bonding?

A

A shared pair of electrons

45
Q

What is meant by dative covalent bonding?

A

A shared pair of electrons from the same element/atom

46
Q

What are the anomalous properties of ice due to hydrogen bonding?

A

Ice is less dense than water due to the hydrogen bonds pulling the molecules apart
Ice has a higher melting point than expected due to the strength of the hydrogen bonds

47
Q

Explain why a molecule would be polar?

A

There is a difference in electronegativities OR
The molecule is not symmetrical so the dipoles do no cancel

48
Q

Describe the structure and bonding of metals and their features

A

Metals have a giant metallic structure, with metallic bonding where positive ions and electrons are attracted.
Metals can carry a current because the delocalised electrons can carry a charge/are mobile
Metals are thermal conductors because the delocalised electrons can pass kinetic energy to one another.

49
Q

Describe the structure and bonding of non-metals and their features

A

Have a simple covalent lattice, has van der waal forces between molecules/temporary dipoles.
Cannot carry a charge

50
Q

Describe the bonding in graphene and what features it allows

A

Single layer of graphite 1 atom thick, has covalent bonds
Delocalised electrons which allows a current, a better electrical conductor than graphite because the electrons can move faster as there is no layers.
Very strong as delocalised electrons make covalent bonds stronger.

51
Q

Describe the bonding in graphite and what features it allows

A

Carbon allotrope, has covalent bonding within atom, with weak induced dipoles holding molecules together.
Has delocalised electrons.
The weak dipoles are broken easily so layers/sheets can slide
Delocalised electrons can carry a current
Strong covalent bonds so high boiling
Insoluble due to covalent bonds

52
Q

Describe the bonding in silicon and the features it allows

A

Crystal lattice structure, similar to diamond

53
Q

Describe the bonding in diamond and the features it allows

A

Crystal lattice structure
High melting point due to covalent bonds, very hard, a good thermal conductor.
Cannot conduct electricity, because it has no delocalised electrons
Insoluble

54
Q

What bonding would NaCl have?

A

Giant ionic lattice

55
Q

How would you reduce the percentage uncertainty?

A

Use a larger mass
Use a mass balance that weighs to 3 or more decimal places

56
Q

How to convert cm cubed to m cubed?

A

Divide by a million

57
Q

How to convert Kpa to pa?

A

Times by 1000

58
Q

What does a smaller ionic radius mean?

A

A bigger enthalpy of hydration because their charge density is higher

59
Q

What does a bigger ionic charge mean?

A

Bigger enthalpy of hydration because the ions can attract water molecules better

60
Q

Is calcium an oxidising or a reducing agent?

A

Reducing

61
Q

What does it mean when temperatures increase and the KP decreases

A

It means the forward reaction is exothermic

62
Q

How do you recrystallise to obtain pure crystals?

A

Dissolve in a minimum quantity of hot water, cool, filter and then dry.

63
Q

What should you do near the end point of a titration with iodate ions

A

Use starch near the end point, a colour change from blue to colourless should occur

64
Q

Why does reactivity decrease down the halogens?

A

Electrons increase down the group which increases the strength of the induced dipole-dipole forces.
This means more energy is needed to overcome/break them/ the intermolecular forces.

Chemistry (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions