Alcohols Haloalkanes And Analysis

Question 1

How do you name alcohols?

Answer 1

Propan-1-ol if -OH is on carbon 1

Propan-2-ol if -OH is on carbon 2

Question 2

What are primary alcohols?

Answer 2

-OH group is attached to the end of an unbranched chain

Question 3

What are secondary alcohols?

Answer 3

-OH group is attached to a carbon atom with two alkyl chains and one hydrogen atom

Question 4

What are tertiary alcohols?

Answer 4

-OH group is attached to a carbon atom with 3 alkyl chains attached

Question 5

What effect does the length of alcohol chains have on boiling point?

Answer 5

As molecules get longer there is more surface contact and so molecules have stronger induced dipole-dipole forces

Question 6

How do boiling points of alcohols compare to those of alkanes?

Answer 6

Bp of alcohols are stronger than corresponding alkanes due to hydrogen bonds between -OH groups: strongest type of intermolecular force

Question 7

What happens to the solubility of alcohols as their chain length increases?

Answer 7

Solubility decreases as chain length increases: aliphatic chain cannot form hydrogen bonds

Question 8

What is produced when alcohols undergo complete combustion?

Answer 8

Water and carbon dioxide

Question 9

How can you get an aldehyde through oxidation of an alcohol? State reagents and colour changes

Answer 9

• react an oxidising agent with a primary alcohol
• heated gently with acidified potassium dichromate
• produces an aldehyde and water
• orange to green

Question 10

How can you get a carboxyl if acid through oxidation of an alcohol? State reagents and colour changes

Answer 10

• react an oxidising agent with a primary alcohol
• heated strongly under reflux with excess acidified potassium dichromate
• produces a carboxylic acid and water
• orange to green

Question 11

How can you get a ketone through oxidation of an alcohol? State reagents and colour changes

Answer 11

• react an oxidising agent with a secondary alcohol
• heat under reflux with acidified potassium dichromate
• will produce a ketone and water
• orange to green

Question 12

Explain esterification

Answer 12

• reacting an alcohol with a carboxylic acid
• this should be done in the presence sulfuric acid at a temp of 80 degrees C
• reversible slow rate reaction
• produces water and an ester, sweet smell

Question 13

How do you name esters?

Answer 13

• First part of the name is the chain that was once attached to the alcohol eg methyl
• the second part of the name is the chain that was once attached to the carboxylic acid group (chain with the double bond o) eg methanoate

Question 14

What is dehydration? Include necessary conditions and reagents

Answer 14

• Type of elimination reaction
• when alcohols are heated at 170 degrees c with concentrated sulfuric acid
• produces an alkene and water
• pi bonds form between adjacent carbons

Question 15

How would you form a haloalkane from an alcohol?

Answer 15

Reagent would be hydrogen halide eg. HCl or HBr

Question 16

What is a primary haloalkane?

Answer 16

Has the halogen at the end of a chain

Question 17

Why are halogens often delta negative in molecules?

Answer 17

• Because it has a higher electro negativity than C or H

- polar bonds in haloalkanes

Question 18

What 2 factors affects the reactivity of haloalkanes?

Answer 18

• Bond enthalpy, decrease down group; more reactive going down group 7 as bonding electrons are further from the nuclei
• polarity of the C-X bond, fluorine is the most electronegative element so electronegativity decreases down the group

Question 19

What is neucleophilic substitution? Eg?

Answer 19

When an atom or group of atoms is exchange for a nucleophile - attracted to the partial positive charge on the carbon atom.
Hydrolysis: water or hydroxide ion solution

Question 20

Explain hydrolysis using aqueous alkali? What is the other form of hydrolysis?

Answer 20

• When a haloalkane is heated under reflux with an aqueous solution containing hydroxide ions
• produces an alcohol and a halide ion

Can be carried out with water, however the rate of reaction is slower

Question 21

What are chlorofluorocarbons?(CFCs)

Answer 21

A class of organic compounds that contain chlorine and fluorine atoms
-As they are inert and non-toxic they are used as firefighting equipment/fire extinguishers/refrigerants

Question 22

What are CFC’s at room temp?

Answer 22

Gases

Question 23

What happens to CFC’s as they rise up into the stratosphere?

Answer 23

They become exposed to UV radiation:

• This causes homolytic fission to occur
• This creates 2 radicals, 1 is chlorine

Question 24

What is the effect of chlorine radicals from CFC’s at the ozone layer?

Answer 24

-Cl radical can compose ozone
-Cl radical reacts with ozone to form ClO radical and O2
ClO radical reacts with ozone to reform Cl radical and 2O2

Question 25

What other radicals react with the ozone?

Answer 25

- In high temperatures or when lightning occurs nitrogen and oxygen can react to make nitrogen oxides - nitrogen monoxide can decompose ozone

Question 26

What is quickfit apparatus?

Answer 26

Heat-resistant glassware, joints must be greased sighting before use

Question 27

How do you conduct distillation?

Answer 27

Equipment: •heating mantle •thermometer •thermometer holder •condenser •collecting flask •round bottom flask -Connect condenser to water supply and place hose with water going out into the sink -pour organic mixture into round-bottomed flask with a few anti-bubbling granules to ensure smooth bubbling -flask should be over a heating mantle to heat the mixture

Question 28

How can you heat under reflux? And why is this necessary?

Answer 28

Necessary to ensure that a reaction mixture does not boil away •pear shaped flask •heating mantle •condenser

Question 29

How can you use a drying agent?

Answer 29

Inorganic salts such as magnesium sulfate and calcium chloride absorb water to become hydrated, they can act as drying agents for other chemicals - add a few spatulas of drying agent - if dying agent clumps, add more - when drying agent remains free-moving, organic product is dry - use gravity and filtration to collect filtrate which is the dry organic product

Question 30

What is redistillation?

Answer 30

Performing multiple distillations | Eg. To purify ethanol and water further

Question 31

How can you seperate immiscible liquids?

Answer 31

Using a separating funnel: 1. Mount funnel on clamp over a reaction vessel 2. Remove stopper and close tap 3. Pour mixture into funnel half way, wash out reaction vessel w/ water and add this mixture to the funnel put stopper back 4. Take the funnel out the ring and invert it, open tap to equalise pressure. Turn tap closed and shake continue to equalise pressure until you no longer hear a whistle. 5. Put the funnel back into the ring and give the mixture time to seperate into layers 6. Remove the stopper, put a beaker under spout and open tap to collect water 7. Using a clean dry beaker open the tap and collect organic product 8. Use drying agent and place organic product into a container

Question 32

How can you test for a haloalkane?

Answer 32

Silver nitrate ethanol and water - white precipitate-chloro - cream precipitate-bromo - yellow precipitate-iodo

Question 33

How can you test for carbonyl?

Answer 33

Acidified potassium dichromate - ketone: no change - aldehyde: orange turns green Fehlings solution - ketone: no change - aldehydes: dark red precipitate Tollens reagent - ketone: no silver mirror - aldehyde: silver mirror

Question 34

How can you test for a carboxylic acid?

Answer 34

Universal indicator -pH of a weak acid Reactive metal -effervescence(hydrogen) Metal carbonate -effervescence(CO2)

Question 35

How can you test for an alcohol?

Answer 35

Warm with equal volume of carboxylic acid and sulfuric acid | -sweet smell of ester

Question 36

What are two examples of compounds with more than one functional group?

Answer 36

Aspirin and Niacin