Chemistry - Chains, Energy and Resources - F322 - Alcohols, Halogenoalkanes and Analysis (2)

Question 1

What are the two methods by which ethanol can be made?

Answer 1

Ethanol can be made by either the hydration of ethene or the fermentation of sugars.

Question 2

What conditions are required for the hydration of ethene?

Answer 2

The hydration of ethene occurs at 300oC and 60 atm in the presence of a phosphoric acid catalyst.

Question 3

In the hydration of ethene, what percentage of ethene is converted to ethanol?

Answer 3

5% of the ethene is converted to ethanol.

Question 4

What enzyme catalyses the fermentation of sugars to produce ethanol?

Answer 4

Zymase

Question 5

What are the strongest type of intermolecular forces?

Answer 5

Hydrogen bonds are the strongest type of intermolecular forces.

Question 6

What makes alcohols less volatile than alkanes of a similar molecular mass?

Answer 6

The hydrogen bonds make alcohols less volatile than alkanes of a similar molecular mass.

Question 7

Define volatiliy.

Answer 7

Volatility is the ease with which a liquid turns to a gas. Volatility increases as boiling point decreases.

Question 8

Solubility of alcohols decreases as what increases?

Answer 8

Solubility decreases as chain length increases.

Question 9

What is a primary alcohol?

Answer 9

In a primary alcohol the -OH group is attached to a carbon atom with no alkyl groups or bonded to one alkyl group.

Question 10

What is a secondary alcohol?

Answer 10

In a secondary alcohol the -OH group is attached to a carbon which is bonded to two alkyl groups.

Question 11

What is a tertiary alcohol?

Answer 11

In a tertiary alcohol the OH group is attached to a carbon atom bonded to three alkyl groups.

Question 12

What is a suitable oxidising agent for primary and secondary alcohols?

Answer 12

Acidified dichromate ions are a suitable oxidising agent for primary and secondary alcohols.

Question 13

What is a primary alcohol oxidised into?

Answer 13

A primary alcohol is oxidised to an aldehyde.

Question 14

When making a carboxylic acid the reaction mixture is usually heated how?

Answer 14

When making a carboxylic acid the reaction mixture is usually heated under reflux.

Question 15

Define reflux.

Answer 15

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

Question 16

What are secondary alcohols oxidised to produce?

Answer 16

Secondary alcohols are oxidised to ketones.

Question 17

What reacts together to form an ester?

Answer 17

An esterification reaction involves an alcohol reacting with a carboxylic acid.

Question 18

When naming an ester, in what order is it named?

Answer 18

The alcohol forms the first part of the name, the alkyl part, and the carboxylic acid forms the -oate part of the name.

Question 19

What is used as the acid catalyst in the formation of esters?

Answer 19

Concentrated sulphuric acid is often used as the acid catalyst in the formation of esters.

Question 20

What is the general formula of the halogenoalkanes?

Answer 20

CnH2n+1X

Question 21

What two factors can affect the rate of hydrolysis of halogenoalkanes?

Answer 21

The polarity and the bond enthalpy can affect the rate of hydrolysis of halogenoalkanes.

Question 22

Which is more important at affecting the rate of hydrolysis of halogenoalkanes, the bond enthalpy or polarity?

Answer 22

Bond enthalpy is more important than bond polarity when it comes to the hydrolysis of halogenoalkanes.

Question 23

What is the calculation for the percentage yield?

Answer 23

% yield = (actual amount, in mol, of product / theoretical amount, in mol, of product) X 100

Question 24

Why are yields of 100% rarely obtained?

Answer 24

• the reaction may be in equilibrium
• other side reactions resulting in byproducts
• reactants may not be pure
• some reactant product may be left behind in the apparatus
• separation and purification may result in loss of some of the product

Question 25

What is the equation for atom economy?

Answer 25

atom economy = (molecular mass of the desired product / sum of the molecular masses of all the products) X 100

Question 26

What is the atom economy of addition reactions?

Answer 26

Addition reactions have an atom economy of 100%

Question 27

Where do most organic molecules produce a peak on an infrared spectrum?

Answer 27

Most organic molecules produce a peak at about 3000cm-1 due to absorption by the CH bond.

Question 28

What is the molecular ion, M+?

Answer 28

The molecular ion, M+ is the positive ion formed in mass spectrometry when a molecule loses an electron.

Question 29

What is the most common method of ionisation in mass spectrometry?

Answer 29

Electron impact is the most common method of ionisation.