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F334 OCR B Chemistry > F334 Models > Flashcards

F334 Models Flashcards

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1
Q

Enaniomers

A

Enantiomers are isomers whose structures are non superimposable mirror images.

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2
Q

Phenol test

A 
Neutral iron (III) chloride 
Turns from yellow to purple
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3
Q

Addition of sodium carbonate to carboxylic acid (but not phenol)

A

Fizzing

Produces CO2

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4
Q

Why is it important to have atom economy?

A

To reduce waste products

To ensure costs are kept to a minimum/ less energy is used

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5
Q

Colorimetry

A

Make up standard solutions of known concentrations
Choose a suitable filter - complementary colour
Zero colorimeter with water
Measure absorbance of standard solutions
Plot calibration curve
Measure unknown solutions
Read off concentration from calibration curve

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6
Q

Why can x act as a base?

-NH2

A

LONE PAIR on N/amine group

Accepts a proton

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7
Q

Cis and trans isomers

A

There are two different groups on each Carbon of a C=C

These groups CANNOT rotate about the double bond

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8
Q

Less trans isomers

Effect of crystallinity

A

Less trans linkages will make the chains less linked so they cannot line up and the crystallinity will be reduced

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9
Q

DNA polymerisation reaction type and other product (with Sugar-phosphate)

A

condensation and water

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10
Q

H bonding between bases

A

parallel dashed lines from the delta positive hydrogen to the lone pair on the nitrogen with a delta negative charge - interaction at 180’. Two bonds between thymine and adenine. (Three between cytosine and guanine).

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11
Q

Successful outcomes of clinical trials

A

No harmful side effects: non-toxic

It works better than standard medicines.

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12
Q

DNA finger prints of the innocent

A

Infringement of personal liberty
Fingerprint not unique; only probability
Techniques used not foolproof
Law might change accessibility

Helps to solve many crimes
Innocent until proven guilty
Future research into disease

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13
Q

Condensation
Polyamide vs polyalkene
Water Absorption

A

-CONH, -NH, amide group allows nylon (a polyamide) to form H bonds with water molecules

No H bonding in neoprene (a polyalkene), so water molecules will force chains further apart
Chain less crystalline
Decrease in imb strength
Therefore Tg lowered

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14
Q

Solvent properties for recrystallisation

A

The solvent should dissolve solute at high temperatures

The solvent should dissolve almost no solute at room/lower temperature

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15
Q

Two stereoisomers would be expected to have different activities in the body

A 
They have different shapes
The active site has a specific shape
One will bind with the active site better than the other
Only one will form ESC
They form ESC with different enzymes

Active site = reception

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16
Q

Why does phenol reaction with NaOH and suggest why product is soluble in water?

A

Has phenol/phenolic hydroxyl groups
These groups are acids and neutralised by NaOH/OH-
Ions form
Ions are soluble

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17
Q

Iron (III) and sodium hydroxide ionic equation

A

Fe3+(aq) + 3OH(aq)- —> Fe(OH)3 (s)

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18
Q

mass spectrum
Species lost
17 m/z value of species lost
What is this species?

A

17 = 16 + 1
OH

A SPECIES LOST MUST HAVE NO CHARGE

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19
Q

Species which form peak on mass spectrum have what charge?

A

+

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20
Q

C14H12O3 + 3 OH- —>

A

C14H12O3 +3OH- —>C14H9(O-)3 +3H2O

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21
Q

Mass peak at 93

A

C6H5O+

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22
Q

Sodium carbonate

A

Na2CO3

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23
Q

One mole of alcohol was reacted with one mole of ethanol chloride —>new functional group

A

Ester

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24
Q

Element oxidation state

A

0

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25
Q

Reducing agent

Allows reduction, gaining electrons

A

Loses electrons
Oxidation number increases
More positive

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26
Q

Following a reaction which produces iodine, I2, as well as uses up H+

A

Colour/absorbance
Iodine
By colorimetry

Concentration
Iodine
By titration

Acidity/pH
H+
By pH meter/titration

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27
Q

The rates of reaction were measured when the amount of reactants used up were small in comparison to the total quantities of reactants present

A

As reactants are used up
The rate will change - decrease

If relatively small amounts of reactants are used up, Concentration will remain almost constant

If relatively smaller amounts of reactants are used up, the rate measured will be for the initial concentrations

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28
Q

C2H3CONH2 + H2O + H+ —>

Acid hydrolysis

A

C2H3CONH2 + H2O + H+ —> C2H3COOH + NH4+

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29
Q

C2H3CONH2 + OH- —>

Alkali hydrolysis

A

C2H3CONH2 + OH- —> C2H3COO- + NH3

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30
Q

NH2 group

Can behave as a base

A

Can accept H+

Has a lone pair of electrons

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31
Q

AmiDe group

A

CONH2

NotNH2

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32
Q

An Amide -NH3 : base?

A

Does not act as a base

Does not gain proton

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33
Q

Unsaturated side groups

React together to form cross links

A

Addition

C=C bonds on side chains of different polymer chains open up and form a covalent bond

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34
Q

Carboxylation reagent

-COOH to -COO-

A

NaOH

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35
Q

[Fe(H2O)6]3+

Shape
Coordination number
Colour

A

Octahedral
6
Yellow

Not green because for II (ee)

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36
Q

Diol and dioic acid

Reaction type

A

Condensation

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37
Q

Cross links prevent dissolving

A

Cross links will prevent chains moving apart
Without cross links, water will force polymer chains apart and so polymer will dissolve
Water will form H bonds with chains COOH or OH groups

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38
Q

Addition vs. Condensation (or elimination) (to form co-product)

A

Addition has no atoms/products are wasted
Only one product
Therefore higher atom economy

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39
Q

Condensation with carboxylic acid: loses OH or H?

A

OH

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40
Q

Water absorbed by polymer

What happens to concentration of dye in solution

A

The concentration of blue dye increased as water was absorbed

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41
Q

Suggest why it is easier to recycle the super-absorbent polymers from used nappies than the polymers from a mixture of used packaging

A

Used packaging consists of many different polymers which need to be sorted first
Lots of other compounds/additives in plastics used for packaging to be removed
Can wash/separate polymer from nappies and then heat to remove absorbed water

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42
Q

Why can a Voltage measured be different from standard?

A

The measured voltage is not done are standard conditions

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43
Q

Describe how the student used a colorimeter to find out how the concentration of the blue dye changed when added to the polymer

A

Select orange filter - complementary colour
Make up dye solutions of different known, standard concentrations
Measure the absorbance of the dye solutions of different known concentrations
Plot calibration graph of absorbance of readings
Add the polymer of known mass to the dye solution and measure the new absorbance
Take measurements until no further change in absorbance over a period of time
Use the calibration curve to find out how the concentration of the blue dye changes to find the concentration of the blue dye at different times

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44
Q

K2FeO4

‘Green’ oxidising agent

A

It is green (eco) because it forms iron III oxide (rust)product which is non polluting/ non toxic
Therefore often they can be out in landfill sites

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45
Q

Compound with ‘sour taste’

A

Vinegar

Ethanoic acid

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46
Q

Ethanol to ethanoic acid

Reagents and conditions

A

Acidified dichromate

Heat under reflux

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47
Q

Base

A

Proton acceptor

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48
Q

Phenol + carbonate

A

NO REACTION

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49
Q

No E/Z
C=C
Ring structure

A

Restricted rotation around the C=C bond
Each C atom in C=C has two different groups attached to it
The two -OH groups can only be on the same side of the C=C because the ring structure will not allow to rotate on opposite sides

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50
Q

Moldm-3 to gdm-3

A

Moldm-3 x gmol-1 = gdm-3

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51
Q

Ester hydrolysis

Reagent

A

Concentrated HCl

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52
Q

Esterification
Coproduct
COOH
OH

A

H2O

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53
Q

Ether (vs. Ester )

A

No C=O

R-O-R

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54
Q

Heating under reflux

A

The condenser is vertical
Mixture is evaporated, condensed, and returned to mixture
No substance is lost from the mixture

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55
Q

In distillation

A

The condenser is sloped downwards/horizontal
Mixture is evaporated, condensed, and collected
Mixture is separated

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56
Q

An increase in water absorption

A

More H bonding

-NH, C=O vs. -O-

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57
Q

Decrease melting point

A

Weaker imb

Less energy to separate chains

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58
Q

Increase in rigidity

A

Decrease in sliding of chains
Increase in aligned chains
Increase crystalisation

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59
Q

flexibility additive

A

Plasticiser

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60
Q

Zwitterions have a high melting point

A

They attract each other very strongly
Form a giant lattice
Ionic bonding is very strong
High heat energy required to separate particles

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61
Q

Thalidomide

Used as a sedative in place of drugs at the time

A 
More effective
Cheaper
Smaller dose required
Fewer side-effects
Can treat other symptoms
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62
Q

Testing of drugs of today to prevent thalidomide tragedy

A

Safety tests on drugs for use during pregnancy
Test to see if drug can pass through placenta
Longer period of testing
Longer clinical trials
Testing on pregnant animals

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63
Q

BrO3- +5Br- + 6H+ —> 3Br2 + 3H20

Why follow with Colorimetry

A

Reactants colourless
Br2 is brown
Change and increase in colour
Change and increase in absorbance in a colorimeter in the reaction

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64
Q

control variable

Measuring Reaction rate

A

Temperature

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65
Q

Rds, slow step

Rate = k [BrO3-][Br-][H+]^2

A

Rds, slow step
Depends upon the species given in the rate equation
In this case, two H+ , 1 of the other species
2H+ and BrO3-
Forms
H2BrO3 intermediate

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66
Q

Some transition metal ions in solutions are coloured

A

Ions absorb specific wavelengths, colours of visible light

Ions transmit complementary colour (wavelengths)

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67
Q

[V(H2O)6]2+

A

Coordination number 6
Shape of octahedral
Water
Dative covalent bond

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68
Q

d-block ions lose electrons from

A

4s first, before 3d

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69
Q

[V(H2O)6]2+
Can react with ammonia to form a new complex ion
Reaction type

A

Ligand substitution

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70
Q

Vanadium compounds can act as homogeneous catalysts because vanadium can exist in several oxidation states

A

True

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71
Q

In heterogeneous catalysis, vanadium can only use s electrons to form weak bonds on the catalyst surface

A

False

3d and 4s

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72
Q

Homogeneous catalysts provide a route of lower activation energy for the reaction

A

True

For any type of catalysis

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73
Q

Forming polyamide

  • COOH
  • NH2
A

Condensation

Water is eliminated, formed, lost

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74
Q

Crystalline polymers

A

Polymer chains are highly ordered/aligned

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75
Q

PPA has more crystalline areas

Gives greater Tm

A

PPA chains are closer together
So imb in PPA will be stronger, more H bonds, more imb
More energy
Will be required to break imb
And melt polymer and allow chains to move over each other

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76
Q

Process to make a polymer more crystalline

A

Cold drawing

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77
Q

What is the opposite of addition?

A

Elimination

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78
Q

Carboxylic acid

imb

A

H bonding

id-id (as does everything)

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79
Q

Ester

COOR

A

pd-pd

id-id (as does everything)

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80
Q

DNA Monomer units

A

Nucleotide

Formed from a pentose(deoxyribose + phosphate + a base)

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81
Q

The monomer units in proteins

A

Amino acids

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82
Q

Suggest why scientists once thought that proteins were more likely to transmit genetic data.

A

Proteins have more amino acids than the bases in DNA from which to construct many combinations to carry genetic data.

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83
Q

Ammonium peroxodisufate

A

(NH4+)2(S2O82-)

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84
Q

More positive E^-o-

A

The stronger oxidising agent

Indicates a greater tendency to attract/accept electrons

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85
Q

State the measurements that would be recorded and indicate how these can be converted into concentrations of iodine

A

Take absorbance readings of the reacting mixture at known times

Convert absorbance readings to iodine concentrations using the calibration curve

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86
Q

Homogeneous catalysis

A

Reactants and catalysing are in the same phase

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87
Q

High resolution mass spectrometry

A

The masses of the different types of atom present are not integers/masses are measured relative to Carbon-12. Therefore Mass Spectrometry gives accurate four decimal place.
Comparison to Mr from database.pdifferent compounds with the same whole number molecular mass will have different Mr values from high resolution spectra.

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88
Q

MS peak at 15

A

12+3
CH3+
Must be positive to cause a peak

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89
Q

Charge on species lost from molecular ion

A

No charge

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90
Q

Adding Ethanoate group
Conditions
Reagents

A

(Esterification)
Heat under reflux
Concentrated HCl
Ethanoic acid

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91
Q

Recrystallisation

Removes both soluble and insoluble impurities

A

Heat the impure sample with solvent with a minimum amount of solvent
(While hot,)Filter to remove insoluble impurities.
Leave filtrate to cool and crystallise
(After crystalisation, ) soluble impurities stay in solution
Filter off crystals, wash with cold solvent and dry.

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92
Q

Clinical trials - questions answered

A

1- Is it safe to be used in humans?
2- Is it effective?
3-Is it better than the standard treatment : an improvement on other drugs?

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93
Q

Adding bromine to two double bonds

C24H31NO + 2 Br2 –>

A

C24H31NOBr4

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94
Q

Fe (II) + 2CH3COOH

A

Fe(CH2COO)2 + H2

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95
Q

Fe atom

A

4s2 3d6

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96
Q

Fe (II)

A

3d6

Lost the 4s2 e-

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97
Q

Fe (III)

A

3d5

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98
Q

Why are Fe (III) ions more stable than Fe (II)?

A

Half filled d orbitals (so less e pair repulsion)

3d5 not 3d6

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99
Q

Cerium (IV) sulfate

A

Ce (SO4)2

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100
Q

Green iron ppt left to stand

Becomes red-brown

A

Red brown ppt iron III hydroxide, hydrated iron III oxide
Fe II ions/ Fe(OH)2 are oxidised (lose electrons) by oxygen.

Fe2+ –> Fe3+ + e-
Fe(OH)2 + O2 –> Fe2O3

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101
Q

Moles in 25cm3 to moles in 1000cm3

A

Moles in 25/25 x 1000

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102
Q

Compound A (carboxylic acid) is Insoluble in water but soluble in alkaline solution

A

COOH –> COO-

COOH functional group
Reacts with alkali to form ion is solution: soluble carboxylate
Carboxylate (COO-) forms bonds with water

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103
Q

IR 3150

A

O-H carboxylic acid

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104
Q

IR 1715

A

Ketone AND OR Carboxylic acid

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105
Q

Colorimeter
Calibration curve used to determine concentration of compound B as purple colour faded (to yellow) in titration flask

Show first order with respect to compound B

A

Use a filter that has complementary colour (yellow)
Put a sample of the reaction mixture into the colorimeter and take absorbance readings at set, regular intervals
Convert absorbance readings to concentrations using the calibration curve

Plot graph of concentration v time or 1/time for reaction
Determine half life from graph on the concentration v time plot
Constant half-life = first order

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106
Q

Peptide link in collagen

A

CONH

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107
Q

Amino acid zwitterion

A

NH to NH+
NH2 to NH3+
COOH to COO-

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108
Q

Enzyme activity less

At temp Higher than optimum

A

Intramolecular/ H bonds break and active site is lost

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109
Q

Enzyme activity is less when pH is changes slightly from its optimum

A

Change in pH affects charges in active site

Ionisable groups are altered

therefore prevents correct interactions between enzyme and substrate

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110
Q

First order

Substrate and enzyme

A

Rate = k x [substrate] x [enz]

111
Q

Explain why at low concentration is substrate, the reaction is first order with respect to substrate.

A

Not all enzymes activities are filled/saturated
Substrate can form a substrate-enzyme complex
Active sites are available for substrates, which can bind to active sites
As the conc of substrate increases in proportion so first order

112
Q

Give the new order of substrate and explain how it arises

A

All active sites are saturated
Ant increase in concentration of substrate will not affect the reaction rate
So order becomes or is zero.
[s]1 –>[s]0

113
Q

Enzymes increase industrial process efficiency

A 
Speeds up reaction rate
Reduces number of steps in a synthesis
Improves the atom economy
Reduces the amount of heat energy required
Easier separation methods 
Enzymes can be reused
Uses less toxic solvents
Fewer organic solvents used
Reduces use of more toxic catalysts
114
Q

Why is a polymerisation between an oyl chloride and an amine group a condensation?

A

A small molecule (HCl) has been eliminated (formed)

115
Q

Why is a diol more environmental than an oyl chloride to undergo condensation reaction with a di amino?

A

Water rather than HCl is forms int the reaction which is toxic, needs to be disposed of

OR Oyl chloride contains chlorine which required extra energy, resources, to make

116
Q

Strongest imb in polyethene

A

Instantaneous dipole indicted dipole

117
Q

Strongest imb in Stanly

  • NH
  • COC
A

H bonding

118
Q

Why does polyethene soften at much lower temp than Stanyl?

A

Imb in polythene are weaker than those in Stanyl
Less energy Needed to break the imb in polyethene and enable chains to slide
Chains can move over each other and polymer softens

119
Q

E/V for H2/H+ half cell

A

0

120
Q

Explain why the acid reacts with zinc but not copper. What is the oxidising agent?

A

Zinc -0.76
Hydrogen - 0
Copper + 34

Oxiding agent : H+
E standard values are measured with respect to H2/H+ half cell which = 0
Therefore, metals with e negative electrode potential value will be oxidised by H+ ions.

121
Q

EDTA has what charge?

A

4-

122
Q

EDTA4- is what dentate?

A

Hexadentate

123
Q

What shape will EDTA4- ligands always be?

A

Octahedral

124
Q

What will the coordination number of EDTA4- always be?

A

Coordination number 6

125
Q

Copper II complex ion formed with EDTA4-

A

[Cu(EDTA)]2-
+2 and -4
-2 total

126
Q

Alcohol to aldehyde

Reagent and conditions

A

Acidified dichromate

Distilled

127
Q

What happened if you don’t obtain an aldehyde?

A

Reflux
Excessive heating
Took place
Excess acidified dichromate was used
Acidified dichromate was not added slowly
Alcohol and aldehyde were oxidised further

128
Q

Ester

A

R-COO-R

129
Q

Ether

A

R - O- R

130
Q

Ethanol plus ethanoic acid

A

C2H5OH + CH3COOH –> CH3COOC2H5 + H2O

131
Q

Esterification conditions

Ethanol and ethanoic acid

A

Concentrated H2SO4 which acts as a catalyst ( absorbs water)

132
Q

Industrial enzyme pros

To prepare organic compounds

A

Reduces number of steps
Increases atom economy
Could be cheaper, faster, reused, carried out at lower temperatures, reduces energy requirement

133
Q

Some people lack an effective enzyme to convert ethanal to ethanoic acid
Enzyme less effective as a result of damaged DNA. Alternation of bases.

A

Enzymes are proteins which a specific sequence is amino acids
If the DNA is damaged, the primary structure of the protein will be altered: the sequence of amino acids in the enzyme will be altered
So the tertiary structure, folding of acids, of the enzyme will also alter
The active site is part of the tertiary structure and is where the reaction with the substrate takes place
An altered active site will not have the correct shape, cannot bind and interact with substrate by forming the correct intermolecular bonds
Substrate cannot bind with active sites
Cannot form substrate enzyme complex
By hydrogen bonding differently

134
Q

Tg below room Temp

A

Will be flexible
Enough energy to break imb
Chains move/slide over each other

135
Q

Tg above room temperature

A

Brittle
Not enough energy to break imb
Chains cannot move over each other

136
Q

Adding an extra methyl side group alters flexibility

A

Chains cannot move over each other easily

137
Q

Addictive to make polymer more flexible

A

Plasticiser

138
Q

Make polymer more crystalline

A

Cold drawing

139
Q

Ester hydrolysis conditions

A

Concentrated acid/ H+ (aq) and water

Heat under reflux

140
Q

Why are addition reactions environmentally friendly?

A

High atom economy (100%)

Few/No waste: few/no atoms wasted

141
Q

:CN- acts as what in mechanisms?

Attached to Carbon chain by a C-C, not C-N

A

Nucleophile

The lone pair of electrons which attack the electron deficient Carbon, not the N

142
Q

H2C=CH3R

E/Z isomerism?

A

No

There aren’t two different groups on each carbon

143
Q

Explain why phenol group compound is able to dissolve with little aqueous alkali

A

Phenol group will react with alkali and form ion

Ionic substances are more soluble in water

144
Q
  • phenol
  • NH2

Plus HCl

A
  • Phenol - no change

- NH3+Cl-

145
Q
  • phenol
  • NH2

Add ethanyol chloride

A
  • Ethanoate group in stead of hydroxyl group in phenol

- NHCO

146
Q

Suggest the reducing agent responsible for the decrease in concentration of potassium manganate (VII) storage in sealed bottles.

A

Water

in dilute aqueous solution conc decreases due to a redox reaction taking place in sealed bottles. Oxygen is also formed in the reaction.

147
Q

Unknown concl postassium manganate

Standardise against sodium ethanedioate

A

Fill burette with MnO4- solution (unknown c)
Use graduated pipette for sodium ethanedioate (known c) to place solution in beaker

Then add MnO4- solution slowly near the end point until there is a permanent pink colour (pale purple)

148
Q

D block catalysis

E.g. cu2+

A

Reacts with one of the reactant to form an intermediate compound
Oxidation state of the transition mental ion changes
New ion/intermediate then reacts to form original transition metal ion
Therefore activation Enthalpy for this reaction is lower than without the transition metal ion

149
Q

Aqueous transition metal ions : catalysis type?

A

Homogeneous

150
Q

Why did the student use initial concentrations of C2O42- and H+ that were much larger than MnO4-

A

So during the reaction only the [MnO4-] would be effectively changing.

concentrations of C2O42- and H+ would be effectively constant.

151
Q

First order half life

A

Constant

152
Q

Copper electron configuration

A

3d10 4s1

153
Q

Cu2+ electron configuration

A

3d9

154
Q

Explain why copper is a transition metal

A

Cu forms an ion with partially filled set of d orbitals.

155
Q

Protecting copper from corrosion

A

Barrier protection: galavanising, paint, grease, which prevents copper reacting with oxygen and water

Sacrificial protection
Coat with strap on blocks of Mg or Zn, galavanising
The more reactive Mg or Zn corrodes instead of Cu

156
Q

Why does iron prevent copper form corroding

A

E standard value for Fe2+/Fe is more negative than that for Cu2+/Cu so Fe reacts and corrodes instead of Cu
So Fe reacts/corrodes instead of Cu

(Stronger reducing agent)

157
Q

Crystallinity

A

How polymer chains are packed together
In an orderly, regular way

How polymer chains are aligned (lined up)

158
Q

Above Tm

A

Polymer melts and becomes liquid

159
Q

Below Tg

A

Polymer becomes brittle because chains cannot move over each other
So break when a force is applied

Blended polymer is more crystalline so imbs are stronger
More energy is needed to separate chains and melt polymer

160
Q

Polymer form corn starch

‘Green’

A

Manufactured from a renewable source

Not manufactured from oil/ natural gas

161
Q

Roasting the chromite ore with sodium carbonate in a air produces gas X

A

CO2

162
Q

The Elements oxidised

A

Electrons lost

Fe+2 to Fe+3
Cr+3 to Cr+6

163
Q

Na2CrO4

A

Sodium chromate (VI)

164
Q

Removing a solid from solution

A

Filtration

Centrifuge

165
Q

Fe 3+ oxidising power Vs. Cr3+

Method of extraction from ore

A

Fe +3 has a greater oxidising strength
Can be reduced by Carbon
The ?pure iron can be made from its ores by Carbon reduction.

166
Q

Full labels for half cells

A

Pt electrode for non mentals
Inverted tube, for H2 to be pumped in at top
Voltmeter attached to electrodes
Salt bridge labelled
Standard conditions: 1moldm-: and 298K/25’C

167
Q

Three ligands
Bi dentate

Coordination number?

A

6

168
Q

Bond angle in octahedral

A

90’

169
Q

*Bidentate ligand

A

It can donate two lone pairs of electrons

To form dative covalent (Co-ordinate) bonds with metal cation.

170
Q

Explain an acid base equilibrium

A

Transfer of a proton

A prom is donated and accepted

171
Q

Electronegativity

A

Ability of atoms to attract electrons in a covalent bond

172
Q

Why is Fe2+ a stronger oxidising agent than Cr3+

A

Fe2+ is a stronger oxidising agent than Cr3+ because the Estandard of Fe3+/Fe half cell is more positive than that of the Cr3+/Cr half cell

173
Q

Proteins to amino acid reaction

A

Condensation

174
Q

Give the chemical reagent and conditions used in the lab to break down casein into its constituent amino acids

Peptide hydrolysis

A

Reagent: concentrated HCl
Conditions: heating under reflux

175
Q

Tertiary structure

A

Overall folding of the protein

The 3D shape

176
Q

Tertiary structure affected by pH

Use example groups

A

Changing pH affects the charges on groups

By lowering pH

  • COO- can be protonated to form COOH
  • NH2 print anted to NH3+
177
Q

Why was a back card placed behind the tissues

Milky, white to colourless

A

To help judge the si appearance if the suspension/ milliners

178
Q

Rate v temp

Roses then falls sharply

A

As the temp increases
Particles have more energy
More collisions have energy grater than the activation Enthalpy
Graph falls because at high temperatures intermolecular bonds break.
Loss of active site - its shape changes

179
Q

When substrate concentration is high, what is its order?

A

Zero order

All active sites are full

180
Q

Problem chemists solve when a suitable dose of the oil for a diabetic patient

Oil - doesn’t dissolve
Skin irritant

A

Dose which is safe
Find out which dilution is Non irritant
How to dissolve, administer oil - how to form a suspension of the oil

181
Q

Thin-layer chromatography

A

Draw a pencil line at bottom of plate and place a drop of mixture and drop of each of the 3 compounds On the line
Place plate In solvent, line above solvent level, and add lid/ cover
When solvent nears top of the plate, remove , dry, plate
Locate spots with UV light, iodine
Compare heights of spots from mixture with the three standard compounds
Or Calculate Rf values of spots and compare those with standards.

182
Q

Phenol and NaOH

A

Phenol reacts
To form salt
Soluble

No phenol In linalool so no reaction
Alcohols do not react with NaOH

183
Q

C= O reduction

A

C-OH

184
Q

Calculating solubility : mass in grams that will dissolve in 1.00 dm^3 at 25’C

A

Proportional to moles of H+

gmol-1 X mol = g that will dissolve

185
Q

Combinatorial chemistry

A

A method for synthesising a large number of similar organic compounds (analogues) in a short time

‘Make a larger number of related compounds together quickly’

186
Q

Esterification

Type and co-product

A

Condensation

Water

187
Q

Polyester imb

A 
Pdpd 
Idid (as does everything)
188
Q

Alkali hydrolysis

Why Reflux

A

Vapours are condensed and turned to liquid
Mixture needed to be heated for a long time to break down polymers, reaction to occur
No reactants or products (vapours) lost
High temp required for reaction

189
Q

Recrystallisation solvent proprieties and process

A

Dissolves salt well at high temp but very little or none at room temp
Use hot solvent
Dissolve in miminum amount of solvent
Leave or recrystallise
Filter off crystals so soluble impurities are left in filtrate, solution
Wash with cold solvent and dry

190
Q

Explain why a substance produces a spectrum showing absorption peaks when irradiated with infrared frequencies.

A

Bonds in molecule absorb specific IR wavelengths.

Absorbing different frequencies causes different bonds to vibrate.

191
Q

Tg

A

Temp below which the polymer turns glassy, brittle

192
Q

PET
Tm 260’C
Heat to 300’C

A

It would melt - turn to liquid

193
Q

A less crystalline polymer

A

Chains are further apart
So weaker intermolecular bonding
So chains Can move over one another more easily

194
Q

C2O42- ( bidentate) ligands and Fe3+

Complex ion formed has change 3-

Coordination number

Shape

A

[Fe(C2O4)3]3-
3+,2-
3+ + -6 =3-
3+ + (2-x3) =3-

3 ligands, but bidentate
Coordination number 6

Shape : octahedral

195
Q

Feasibility of Redox reaction using E cell

A

E standard electrode potential of … is more negative than that of …

E cell is +1.26 V so reaction is feasible.

196
Q 
Titration
Conc. Ethandioate solution can be found by titration
Standard postassium manganate (VII)
Acidic conditions
Slow at room temp.
Needs to be heared at 60'C
A

Manganate (CII) solution in burette
Pipette known volume of ethanedioate solution into flask
Add acid
Warm solution to 60’Titrate Until pink colour persists (because MnO4- unreacted being added and is in excess)
No indicator needed because only MnO4- (aq) is coloured. Or a colour change takes place during the reaction.

197
Q

Progress of this reaction

A

Pink colour fades
Colour effervescence
Titration or colorimetry

198
Q

Zwitterion

A

Forms a negative and positive charge

199
Q

Changes in reaction rate during progress of reaction?
Colour change explained
Catalyst?

A 
MnO4- purple to Mn2+ colourless
Mn2+ act as a catalyst
As reaction progresses
Rate increases
Catalyst is formed
Rate decreases as as reactants are used up.
200
Q

Zwitterion with a phenol group in an aqueous solution

Acidic, alkaline , or neutral solution?

A

Acidic because it has a phenol group

201
Q

Suggest why only one stereoisomers is effective in treating the disease

A

They have different shapes

Only one will bind to receptor, active, site

202
Q

DOPA has many adverse side effects

Suggest why it is still used to treat pArkinson’s

A

Benefits outweigh side effects

It is more effective than other drugs, less adverse side effects

203
Q

Titration
25.0 in pipette
Originally in 100 cm3 solution
Moles of original solution compared to titration?

A

Moles x 4

204
Q

Overall order

A

The powers in rate equaton added

Rate = k X [] x[]^2
Overall order = 3

205
Q

Alcohols to aldehyde

A

Acidified dichromate

Add reagent to alcohol and distilled off aldehyde as it is formed

206
Q

Rds

A

Slow step
Species in are in rate equation
The number of moles indicate the order
1 mole means first order, two moles means second order

207
Q

Half equation formation Fe II ions

A

Fe–>Fe2+ + 2e-

Oxidation

208
Q

Ionic equation
Formation green rust
Fe II

A

Fe2+(aq) + 2OH-(aq) –> Fe(OH)2(s)

(Ionic) precipitation

209
Q

Oxidation red brown rust

A

+3

210
Q

Why would green rust form instead of red

Why Fe II vs Fe III

A

Low oxygen Concentration around pipes

211
Q

Green rust on a steel surface can be removed by converting the rust into a soluble iron compound

Rub surface with sulphuric acid

Compound formed ?

A 
Iron (II) sulphate (VI)
Fe(2+)
SO4(2-)
    O4=-8
S in SO4(2-) =+6
-8+6=2-
212
Q

Complex

A

Central metal ion (cation) bonded to ligands (negative molecules)

213
Q

Ligand

A

Molecule which has a lone pair which forms a dative covalent coordinate bond

214
Q

Polydentate

A

A polydentate ligand can form more than one bond, donating at least two lone pairs to central atom, ion
Has more than one atom with a lone pair which are used to bond.

215
Q

Possible shapes of complexes with four coordinate bonds

A

Square planar

Tetrahedral

216
Q

25 cm3 solution in grams

A

25 g

217
Q

Colorimetry

A

Mix a fixed volume of B with a constant volume of each NaOH solution
Zero calorimeter
Use suitable filter of complementary colour
Measure absorbance of sample at known times/over time
Dilute H by known amounts
Measure absorbance
Plot graph of absorbance against [B]
[B] v absorbance
To get linear relationship
Confirm proportional

218
Q

How would student do this.

Determine order with respect to concentration B

A

Vary concentration of B

Keep cocnetrai m of NaOH/OH- constant

219
Q

How can one acid be polymerised

A

It has two functional groups which can react
New functional group is an ester
Condensation polymerisation

220
Q

Polymer from glucose

Advantage food packaging

A

Biodegradable, breaks down in soil
Renewable, sustainable source
Avoids use of fossil fuels (not made from crude oil)

221
Q

Tg

A

Temp below which an polymer becomes brittle, glassy

222
Q

Above Tg

A

Polymer becomes flexible, will bend because chains can slide over each other

223
Q

PPO (With Tangled chains)

Tg higher

A

Has tangled chains which need more energy to slide over each other

Tangled, less ordered chains cannot move, slide, over each other easily across each other

224
Q

Explain this difference in garment stretch in terms of Imb

bullet proof

A

Chains are straighter
So chain molecules are closer together
Imb between chains will be stronger

( polyamides - so H bonding )

225
Q

Polyamides

A

H bonds
Pd-pd
And idid

226
Q

Adding COCl to a compound

A

Acylation

Elimination

227
Q

Give a chemical reason why arsenic might be able to replace phosphorus

A

As and P are in the same group in the periodic table

Both have five electrons in outer shell

228
Q

Suggest a formula of H2AsO4- in strongly acidic solutions

A

H3AsSO4

229
Q

Amine groups have basic properties

A

N atom has a lone pair of electrons

Which can accept a proton/H+

230
Q

Amide

A

NHCO

231
Q

Better water absorption polymers

A

Form more H bonds

232
Q

Polyester

A

pdpd

Idid

233
Q

Polymers with same linkage can have different strengths

A

Longer chains
More imb in longer chains

Polymer chains closer
Intermolecular bonds are stronger

Shorter monomer chains
More imb between chains

234
Q

Adding recycled steel

A

Lower controlling temperature of contents of furnace
Absorbs heat
Prevents getting on hot: thermal shock

235
Q

Suggest a modification chemists might make to structures of medicines to make more effective

A

Change functional groups

236
Q

Thin layer chromograph material

A

plate/ sheet

Not ‘paper’

237
Q

Iron II to iron III by oxygen

Sodium hydrogen carbonate non return valve

A

Iron II to iron II can be oxidised by oxygen in the air
NaHCO3 reacts with acid to form CO2
Air/gas dispelled which cannot return

238
Q

DNA fingerprint- ownership?

Follow specific question stem

A

Choose to have stored
To find out about relatives, ancestors
To diagnose illness

Required to give DNA sample
They are criminal suspects

Choosing to have data removed
Infringes privacy
They have been found not guilty

239
Q

Adenine-thymine and guanine-cytosine base pair bonding pair differences
How the specific paring suggests a copying mechanism for the replication of DNA

A

Adenine bonds to thymine with two hydrogen bonds, whereas guanine bonds to cytosine with three hydrogen bonds.

These hydrogen bonds break during DNA during DNA replication,.
Two single stands are formed.
Each base on these strands forms H bonds to new complementary base

240
Q

Explain the effect of increasing pH has on the structure of the part of the protein formed.

A
  • COOH will lose proton and form carboxylate ions, -COO-

- No NH2+ or NH3+

241
Q

Explain why the -OH group has acid properties in carboxylic acid, but not alcohol

A

The ion formed from carboxylic acid is more stable than the ion formed from the alcohol, because the in alcohol ion e.g ethoxide ion the negative charge is located on the oxygen, but in th carboxylic acid, Ethanoate ion, the charge is spread over the CO2- group

As the ion formed from ethanoic acid is more stable, the position of equilibrium moves to the right (products) and therefore a high concentration of H+ is present and ethanoic acid is more acidic

242
Q

Why Phenol is more acidic than ethanol

A

The phenoxide ion is more stable than the ethoxide ion because the negative charge is spread, delocalised, into the benzene ring,
Whereas the ethoxide ion charge is located on the oxygen
As the phenoxide oxide ion is more stable, the position of the equilibrium,lies more to the right (products)
C6H5-OH –> C6H5O- + H+
Therefore a higher [H+] is present which means phenol Is more acidic

243
Q

Vacuum filtration
Hirsch filter funnel, sintered disc
Buchner funnel, filter paper, Sintered disc

A

For separation of a solid rapidly from the solution, the filtrate

244
Q

Fe(OH)2
Fe (OH)3
[Fe(H2O)6]2+
[Fe(H2O)6]3+

Colours?

A

Fe(OH)2 - GREEIIN
Fe (OH)3 - RED
[Fe(H2O)6]2+ -GREEIIN
[Fe(H2O)6]3+ - YELLOW/BROWN

245
Q

[Cu(H2O)6] 2+
[Cu(NH3)4]2+ or [Cu(NH3)4(H2O)2]2+
Cu(OH)2
[CuCl4]4-

Colours?

A

[Cu(H2O)6] 2+ - BLUE
[Cu(NH3)4]2+ or [Cu(NH3)4(H2O)2]2+ - ROYAL BLUE
Cu(OH)2 - PALE BLUE
[CuCl4]4- - YELLOW

246
Q

[Co(H2O)]2+
[CoCl4]2-

Colours?

A

[Co(H2O)]2+ - PINK

[CoCl4]2- - BLUE

247
Q

Nylon naming

Nylon-6,4

A

Nylon - (no. C in diamine),(no. c in dioic)

Nylon - 6,4

6 C in the diamine monomer and 4C the dioic monomer

Alphabetical - amine first, carboxylic acid second

248
Q

Alkyl groups on amino acid naming order

A

Alphabetical order as always

249
Q

Suitable locating agent for amino acids in chromatography

A

Ninhydrin

250
Q

Kevlar properties

Poly aromatic amide or ‘aramid’

A 
Fire resistant
Extremely strong
Can be made into flexible fibres
Highly crystalline
Low density
Resistant to chemical attack
Does not corrode
20 X stronger than steel of same mass
Chains are flat because of benzene ring
Chains are held together by H bonding
Rigid, ordered polymer molecules - maximises H bonding
251
Q

Peek properties

Poly ether ether ketone
Halogen arene

A

High melting point

Resistant to oxidation

252
Q

Green chemistry in manufacturing polymers

A 
Recycling 
Producing energy
Producing chemical feedstocks
Degradable polymers
Minimising hazardous waste during raw material production and resulting polymers
Decreasing Carbon emissions
253
Q

Degradable polymers

A

Biopolymers are made by living organisms and broken down by bacteria
Synthetic biodegradable polymers are broken down by bacteria
Photodegradable plastics
Broken down by sunlight

254
Q

Keeping track of composition of steel in BOS process - basic oxygen steel making

A

Ionic emission spectroscopy
Steel made into electrode
Each element present emits a characteristic line spectrum, the intensity of lines proportional to atom conc.

255
Q

Recycling polymer pros

A

Conserves fossil fuels feedstock
Reduces energy consumption
Reduces need for expensive landfills - plastics do not decompose readily when buried, limited spaces to fill
Reduces CO2, NO, and SO2 emissions caused by burning plastics

256
Q

Recycling polymer cons

A

The plastics have to be sorted

This is a very expensive process

257
Q

How are polymers recycled?

A

Chemically
conversion back to monomers (depolymerising)
Only practical with high quality, single material waste - not co-polymers, works for some polyesters and polyamides

By cracking
Polymer is broken into smaller molecules which are used as feedstock in the chemical industry

By chemical recycling
Sorted into polymer type expensive manually, IR, X-Ray. Then melted, shredding, granulating, of waste plastics.

Is burning an option?
Impact on environment
Harmful emissions, such as toxic gases, and smoke/ash
However Incinerators can be used which generate heat and power but tech need to be developed to trap harmful emissions

258
Q

High positive numbers of electrode standard potential means

A

Strongly oxidising

Gain electrons

259
Q

High negative numbers for electrode standard potential means

A

Strongly reducing

Lose electrons

260
Q

Feasibility of REDOX reactions

A

Construct electrode potential chart

Use it to make predictions about whether a reaction could occur

Use the half equations to give overall reaction

E electrode cell potential value - the more positive, the more feasible.

261
Q

Polymer chain length

A

The longer, the stronger, increases points of contact

262
Q

Polymer side groups

A

Polar side groups
e.g. Cl in PVC
Stronger bonding - pdpd

263
Q

Polymer branching

A

Straight, unbranched, polymers pack together more closely
Increases points of contact
Stronger

264
Q

Stereoregularity

A

Packing is more closely if side branches are arranged regularly e.g. Poly(propene)
Stronger imb

265
Q

Chain flexibility

A

HC chains flexible

Many orientations

266
Q

Benzene in polymer

A

Increases rigidity

Increases strength

267
Q

Cross linking in polymers

A

Linked by covalent bonds
Makes polymer harder
More difficult to melt
Thermosetting

268
Q

Longer chains

A 
Stronger polymers
More point contact, closer packing, stronger imb
Increases tensile strength
More tangled together
Increases difficulty for sliding 
Less flexible
269
Q

Crystalline polymers

A

Polymers with extensive crystalline regions
More ordered, closely aligned
No bulky side chains or extensive branching
Regular chain structure

Increase in crystallinity 
Increase in strength
Decrease in flexibility 
Increases packing closely
Increases imb
Decreasing sliding, increase rigidity
270
Q

Amorphous polymers

A

Opposite of crystalline
Increases flexibility decreases imb
Decreases close packing
Increases sliding

271
Q

Flexibility

A

Depends on sliding

272
Q

Why recycle steel?

A

Saves energy
Digging and extracting new ore needs a lot of energy and generates pollution
No need to dispose into landfills
Reduces waste
Aerosols need special facilities - dangerous if not completely empty

273
Q

How is steel recycled?

A

All steel packaging can be recycled, except aerosols
Cleaning by incineration
Magnetic properties help sorting
Composition of new steel easily adjusted
Scrap steel is used to reduce temperature - acts as a coolant (absorbs heat), added to the converter before the molten iron is poured in to help reduce thermal shock

F334 OCR B Chemistry (1 decks)

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