WM

Question 1

Describe alcohols

Answer 1

• polar due to OH group/bond
• higher boiling points compared to alkanes
• form hydrogen bonds
• solubility decreases as chain length increases as the hydrocarbon chain won’t bond with water
  -longer chain will have more influence than -OH group

Question 2

Describe a primary alcohol

Answer 2

• has -OH bonded to a carbon bonded to ONE other carbon atom
• will initially oxidise to aldehydes
• further oxidises to carboxylic acid

Question 3

Describe a secondary alcohol

Answer 3

• has -OH bonded to a carbon that is bonded to two other carbon atoms
• oxideised to ketones by heating under reflux

Question 4

Describe a tertiary alcohol

Answer 4

• has -OH bonded to carbon that is bonded to 3 other carbon atoms
• does not oxidise as no hydrogen present

Question 5

Oxidation will only take place if

Answer 5

There is a hydrogen atom on the carbon

Question 6

What is a carbonyl group

Answer 6

C=O

Question 7

Describe a ketone

Answer 7

The carbonyl group is within the chain
- named using -one

Question 8

Describe aldehydes

Answer 8

• the carbonyl group is at the end of the chain
• named using -al

Question 9

Define reflux

Answer 9

The continual boiling and condensing of a reaction mixture to ensure that the reaction takes place without the contents of the flask boiling dry
- a safe method for heating reaction involving volatile and flammable liquids

Question 10

Carboxylic acids can be tested for using…

Answer 10

Sodium carbonate
- will produce CO2

Question 11

What oxidising agent can be used to oxidise primary and secondary alcohols?

Answer 11

Acidified potassium dichromate
- K2Cr2O7/H2SO4
Will turn orange to green (reduced)

Question 12

Describe creating a aldehydes

Answer 12

• gentle heating with acidified potassium dichromate
• distilled immediately
• CnH2n+1COH

Question 13

Describe creating a carboxylic acid

Answer 13

• stronger heating(reflux) with excess acidified potassium dichromate
• CnH2n+1COOH

Question 14

Describe creating a ketone

Answer 14

• secondary alcohol
• heat with acidified potassium dichromate
• CnH2n+2CO

Question 15

Define an elimination reaction

Answer 15

Reaction where a small molecule is removed from a compound

Question 16

Define dehydration reaction

Answer 16

When water is removed from a compound

Question 17

Define substitution reaction

Answer 17

When an atom or group in a molecule is replaced by another atom or group

Question 18

Define esterification

Answer 18

Making an ester
- the reaction of an alcohol with a carboxylic acid to produce an ester and water

Question 19

Define a condensation reaction

Answer 19

When two molecule come together to form a third pls a small molecule

Question 20

Describe the dehydration of an alcohol

Answer 20

• heated at 300c And Al2O3 catalyst
• or refluxed with either conc. phosphoric acid or conc. sulfúrico acid as catalyst

Question 21

Describe esters

Answer 21

• used as adhesives and solvents in the chemical industry
• have strong flavours/aromas

Question 22

Describe ethers

Answer 22

• contain an oxygen atom between two carbon atoms
  -O-

Question 23

What are the 3 tests for salicylic acid

Answer 23

• an aqueos solution of the compound will be weakly acid ice due to -COOH group
• will ract with alcohols to rm esters with strong pleasant odour
• will turn iron (iii) chloride solution purple - due to phenol group

Question 24

The -OH group can occur…

Answer 24

• in carboxyl group of a carboxylic acid
• as a primary,secondary or tertiary alcohol
• attached to benzene ring as a phenol

Question 25

The -OH reacts with water and is…

Answer 25

Acidic - water dissociates to a small extent to create an weak acid

Question 26

What is the rend in acidity

Answer 26

(Least) ethanol< water

Question 27

What happens when phenols and carboxylic acids react with a strong base

Answer 27

- ionic salt is formed -will stay in solution after reaction - only phenols and carboxylic acids are strong enough to react

Question 28

Only ____________ are acidic enough to react with carbonates to form_____

Answer 28

- carboxylic acids - CO2

Question 29

What is the test for phenols

Answer 29

Iron (III) chloride - turn from yellow to purple The -C=C-OH (enol group) only found in phenols forms a purple complex with Fe**3+**

Question 30

Esters can be made by

Answer 30

Phenols reacting with acid anhydrides under alkaline conditions

Question 31

What are the 12 key principles of green chemistry

Answer 31

- better atom economy - prevention of waste products - less hazardous chemical synthesis - design safer chemical products - use safer solvents - lower energy usage - use renewable feedstocks - reduce reagents used and the number of steps - use catalysts and more selective catalysts - design chemical products for degradation - employee real time process monitoring - use safer chemical processes

Question 32

Describe recrystallisation

Answer 32

Used to purify solide crude organic products with small amounts of impurities - choose a suitable solvent that only the desired compound dissolves in when warm Dissolve —> filter —> allow crystals to form —> vacuum filter —> wash and dry

Question 33

Describe thin layer chromatography

Answer 33

- relies on the fact that different organic compound have different affinities for a particular solvent, will be carried through chromatography medium at different rates - silica plate used - used to find Rf value

Question 34

how do you find the Rf value

Answer 34

Distance travelled by spot/ solvent front - will by less than 1 - specific to a compound

Question 35

Describe melting point determination

Answer 35

- melting points can be used identify pure solids - if impure the m.p. Will usually be lower - use published values to identify substance