Module 2 Alcohol, Halogenalkanes And Analysis

Front 1

Volatility?

Back 1

The ease that a liquid turns into a gas. Volatility increases as boiling point decreases.

Front 2

Volatility and boiling point of alcohols?

Back 2

Hydrogen bonds are the strongest type of intermolecular forces. The relatively high melting and boiling points of alcohols results from the presence of hydrogen bonds.

Front 3

Presence of hydrogen bonds causes..

Back 3

Alcohol molecules results in alcohols having a lower volatility than alkanes of similar molecular mass.

Front 4

Solubility of alcohols?

Back 4

Dissolve in water because hydrogen bonds form between the polar O-H groups of the alcohol and water molecules.
Solubility decreases as chain length increases.
Larger part of the alcohol molecule is made up of a non-polar hydrocarbon chain.
Hydrocarbon chain does not form hydrogen bonds with water molecules.

Front 5

Primary alcohols?

Back 5

The -OH group is attached to a carbon atom with no alkyl groups or bonded to one alkyl group.

Front 6

Secondary alcohols?

Back 6

The -OH group is attached to a carbon atom bonded to two akyll groups.

Front 7

Tertiary alcohol?

Back 7

The -OH group is attached to the carbon atom bonded to three alkyl groups.

Front 8

Oxidation of secondary alcohol?

Back 8

Oxidised by acidified dichromate ions to produce ketones. Ketones cannot be oxidised further.

Front 9

Oxidation of tertiary alcohols?

Back 9

resistant to oxidation.

Front 10

Oxidation on primary alcohols?

Back 10

On gentle heating with acidified potassium dichromate, it can be oxidised to produce an aldehyde.

Front 11

Reflux?

Back 11

Continual boiling and condensing of a reaction mixture to ensure that the reaction takes place without the contents of the flask boiling dry.

Front 12

Esterfication?

Back 12

Reaction of an alcohol with a carboxylic acid to produce an ester and water.

Front 13

Dehydration?

Back 13

An elimination reaction in which water is removed from a saturated molecule to make an unsaturated molecule.

Front 14

What are esters used as?

Back 14

Adhesives and solvents in the chemical industry. Flavours and fragrances of different esters are widely used to produce food flavourings and perfumes.

Front 15

Dehydration of an alcohol?

Back 15

Alcohol can be dehydrated to form an alkene in the presence of an acid catalyst.
Example of elimination reaction.
H3PO4 or H2SO4 are suitable acid catalysts.

Front 16

Preparing an ester?

Back 16

In a boiling tube, add 1cm of the carboxylic acid to 1cm of the alcohol. Carefully adding a few drops of concentrated sulphuric acid.
Place the boiling tube in a hot water bath at about 80 degrees for five minutes.
Pour product in beaker of cold water.
You will see oil floating on surface of water.

Front 17

What happens in esterification?

Back 17

In the reaction the O-H bond in the alcohol is broken and water is formed. The water molecule comes from the OH of the carboxylic acid group and the H in the alcohol group.

Front 18

Reactivity of halogenoalkanes?

Back 18

Halogen atoms are more electronegative than carbon atoms.
The bonded electron pair is attracted more towards the halogen atoms that towards the carbon atom.
The result is a polar bond.

Front 19

Hydrolysis?

Back 19

Reaction with water or aqeuous hydroxide ions that breaks a chemical compound into two compounds.

Front 20

What have halogenoalkanes been used as in the past?

Back 20

Referigants, aerosol propellants, degreasing agents and dry cleaning solvents.

Front 21

Hydrolysis of halogenoalkanes?

Back 21

When halogenoalkanes react with an aqueous solution of hot hydroxide ions, a nucleophillic subsitution reaction occurs. The product of this reaction is an alcohol.
Aqueous sodium hydroxide is commonly used, but any aqueous hydroxide is suitable for this reaction.

Front 22

What is nucleophillic substitution?

Back 22

Type of substitution reaction in which a nucleophile is attracted to an electron deficient centre or atom, where it donates a pair of electrons to form a new covalent bond.

Front 23

Infrared radiation, amount of vibration depends on?

Back 23

The bond strength, the bond length and the mass of each atom involved in the bond.

Front 24

What do most bonds vibrate at?

Back 24

300-4000cm-1

Front 25

Uses of infrared spectometry?

Back 25

Monitoring the degree of unsaturation in polymers.
Quality control in perfume manufacture.
Drug analysis.

Front 26

O-H (hydroxyl) group in alcohols peak?

Back 26

3200-3550

Front 27

The C=O (carbonyl) group in aldehydes and ketones?

Back 27

1640-1750

Front 28

The COOH (carboxyl) group in carboxylic acidss?

Back 28

2500-3300 and 1640-1750

Front 29

Uses of mass spectrometry?

Back 29

To indentify unknown compounds.
To determine the abundance of each isotope in an element.
To gain further about the structure and chemical properties of a molecule.

Front 30

Examples of mass spectrometry use today?

Back 30

Analysing molecules in space.
Detecting traces of toxic chemicals in contaminated marine life.
Detecting banned substances such as steroids in athletes.
Monitoring the breath of patients during surgery whilst under anaesthetic.

Front 31

First mass spectrometer?

Back 31

Ions were first generated in a discharge tube.
The ions were then passed through a magnetic field and deflected from their original path.
The ions were finally detected on a photographic plate.

Front 32

Yields of 100% are rarely obtained, why?

Back 32

The reaction may be at equilbrium and may not go to completion.
Other side reactions may occur, leading to by-products.
The reactants may not be pure.
Some of the reactants or products may be left behind in the apparatus used in the experiment.
Separation and purification may result in the loss of some of the product.

Front 33

A limiting reagent?

Back 33

Substance in a chemical reaction that runs out first.

Front 34

How is percentage yield calculated?

Back 34

Actual amount, in mol, of product divided by theoretical amount, in mol, of product x 100

Front 35

How to measure atom economy?

Back 35

Molecular mass of the desired product divided by sum of molecular masses of all product x 100

Front 36

How can atom economy benefit society?

Back 36

By using processes with a higher atom economy, chemical companies can reduce the amount of waste produced.

Front 37

What do we do with by products?

Back 37

By-products are often considered as waste and have to be disposed of. This is costly and poses potential environmental problems.
By-products may be sold on or used elsewhere in the chemical plant.

Front 38

What does atom economy consider?

Back 38

Not only desire products but also the by products of a chemical reaction. Describes efficiency of a reaction in terms of all the atoms involved.

Front 39

Atom economy and type of reaction?

Back 39

Addition reactions have a 100% atom economy.
reactions involving substitution or elimination have an atom economy less than 100%

Front 40

How a mass spectomerty works?

Back 40

Sample in introduced via a sample inlet.
Sample molecules of ionisation include electron impact, chemical ionisation, use on an electrospray and even lasers.
Ions are propelled into a mass analyser.
Ions are separated according to their mass to charge ratio.
Ions are detected. A mass spectrum is generated by a computer software.

Front 41

Mass spectra of elements?

Back 41

The mass to charge ratio in all mass spectra is shown as m/z m is the mass and z is the charge on the ion.