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OCR A-Level Chemistry Salters B > What's In A Medicine > Flashcards

Flashcards in What's In A Medicine Deck (24)
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1

Why do alcohols have a higher boiling point than their corresponding alkanes?

The -OH group on the alcohol is able to form hydrogen bonds which require more energy to break

2

What is the difference between a primary, secondary, and tertiary alcohol?

Primary: -OH group bonded to a carbon bonded to one other carbon

Secondary: -OH group bonded to a carbon bonded to two other carbons

Tertiary: -OH group bonded to a carbon bonded to three other carbons

3

Oxidation of primary alcohols

Products: Aldehyde made first, if there is excess oxidsing agent then a carboxylic acid is formed

Oxidsing agent: Acidified potassium dichromate (VI)

Final Colour of reaction mixture: Green

4

Oxidation of secondary alcohols

Products: Ketone

Oxidsing agent: Acidified potassium dichromate (VI)

Final colour of reaction mixture: Green

5

Oxidation of tertiary alcohols

Products: Does not oxidise

Final colour of reaction mixture: Orange

6

How does reflux work

Liquid is boiled in a vertically mounted condenser so the vapour condenses and returns back into the reaction mixture

Used for heating volatile and flammable liquids

7

Dehydration of alcohols

Alcohols can loose a molecule of water to form an alkene

Conditions: Alumina (Al2O3) catalyst at 300°C OR reflux with concentrated sulphuric acid

Dehydration is an example of a elimination reaction

8

Substitution reactions will alcohols

Nucleophilic substitution with halide ions in the presence of a strong acid

9

Esterification with carboxylic acids and acid anhydrides

Carboxylic acid:
Alcohol + Acid --> Ester + Water
Small amount of concentrated acid as catalyst
Named by alcohol then acid

Acid anhydride:
Alcohol + Acid anhydride --> Ester + Acid
Higher yelid of ester
Named by alcohol then anhydride

10

Ethers

General formula of R-O-R

Structural isomers of alcohols

11

Which molecules contain a hydroxyl group

Alcohols, phenols, and carboxylic acid

12

The order of acidic strength; water, carboxylic acids, phenol, alcohol

Alcohol < Water < Phenol < Carboxylic Acids

13

Reactions with carbonates

Only carboxylic acids have a high enough concentrations of H+ ions to produce carbon dioxide on reactions with carbonates

Alcohols and phenols will not react

14

How to test for phenols

Reaction with iron (III) chloride

If phenol present, the mixture turns purple

15

Ester formation with phenols

Phenol + Acid anhydride --> Ester + Acids
Under alkaline conditions

Phenols do not reaction with carboxylic acids to produce esters

16

Equation linking speed of light, wavelength, and frequency

Speed of light = Wavelength x Frequency

17

What does quantise mean

Molecules must take a small number of definite energy values rather than any energy values

18

Different types of bond deformation

-Symmetric stretch
-Asymmetric stretch
-Symmetric bend

19

Two most important regions on IR spectra

-OH group, around 3000
C double bond O, around 1600

20

Fingerprint region

The region below 1500 which is characteristic of the particular molecule

21

What can be told from mass spectrometry

-The molecular ion, M+
-The fragment pattern
-The relative abundance of fragment ions

22

Recrystallisation

1) Seleft a solvent in which the desired substance is very soluble at high temperatures and and insoluble at low temperatures
2) Dissolve the mixture in the minimum quantity of hot solvent to better the yield
3) Filter to remove any insoluble impurities
4) Leave to cool until crystals form
5) Collect crystals by vacuum filtration
6) Leave the crystals to dry

23

Thin Layer Chromatography

Used to test the purity of a substance

24

Melting point determination

Used to test the purity of substances. A pure compound should melt within 0.5°C of it's true melting point