Practical 10b: Synthesis and Purification of Ethyl Ethanoate Flashcards

1
Q

what are anti bumping for

A

prevent large bubbles from forming

prevents vigorous bubbling

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2
Q

why isn’t a bunsen burner used as a heat source?

A

ethanol is flammable

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3
Q

why is the cold water entering the condenser from the bottom rather than the top?

A

to completely fill the condenser with cold water

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4
Q

why is it essential to have an open top at the top of your condenser?

A

to prevent pressure from building up

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5
Q

why is sodium carbonate used to wash the mixture?

A

to react and remove any excess ethanoic acid which would be a contaminant

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6
Q

why is the stop cock repeatedly opened after every inversion?

A

to prevent pressure from building up

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7
Q

what is the point in adding anhydrous calcium chloride/sodium sulfate to the washings?

A

to remove unwanted water

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8
Q

why is the aqueous layer below the organic layer?

A

its more dense

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9
Q

name the process that we purify the ester

A

distillation

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10
Q

why would the ester have a lower boiling point than the starting ethanoic acid and ethanol starting materials?

A

no hydrogen bonding between molecules

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11
Q

why should the end of the thermometer be level with the condenser?

A

to accurately measure the boiling point of the vapour

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12
Q

how can we qualitatively observe at an ester has been made?

A

fruity smell

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13
Q

what is the boiling point of ethyl ethanoate ?

A

77.1 degrees C

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14
Q

why is sodium carbonate added to reaction mixture in separation of products?

A

This neutralises the unreacted acids

helps to separate the ester into an oily layer

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15
Q

two reasons stopcock opened

A

The separating funnel is inverted and the stopcock opened to release the pressure

The stop cock is opened so that the aqueous layer drains away and then the ethyl ethanoate can be drained into a clean beaker

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16
Q

why is sodium sulfate added during separation

A

to absorb water and dry the ethyl ethanoate

17
Q

how is product separated

A

immiscible layers separate

18
Q

hazards

A
  • ethanol is flammable

- ethyl ethanoate is toxic , flammable + has a strong odour, should be handled in fume cupboard

19
Q

how can an ester be identified

A

using bp of ester
, or smell

ester can then be hydrolysed and the resulting carboxylic acid purified by recrystallisation and its melting pint checked against known values

20
Q

The acid hydrolysis of an ester is very slow, how can the process of formng the c acid be sped up

A

The acid hydrolysis of an ester is very slow,

so it must be heated under reflux with an acid catalyst to make the carboxylic acid