required practical 10 - organic

Question 1

Making ethyl ethanoate notes - prep

Answer 1

-need to reflux - reaction is slow due to covalent bonds
-reactants added slowly - reaction is exothermic - disspiate heat to prevent the reaction from spilling / formation of side products
-condenser is used - vertical - water in at bottom to ensure condenser is allways filled
-no stopper to avoid pressure build up
-antibump granules - prevent bumping
-flammless method used as products often flammable
water ath over tripod - creates a safe enviro as soltuion not in contact with the flame

Question 2

Making ethyl ethanoate notes - isolation

Answer 2

-use sodium carbonate to make a saturated solution - use up aicd to create salt water
-invert sepaeritng funnel after transfer - relase pressure due to the buildup of CO2 - open and close the tap
-allow layers to settle - imiscible liquids
-run off top layer but not organic
-transfer and add sodium sulfate so that any water is absorbed

Question 3

Making ethyl ethanoate notes - purification

Answer 3

-dont distil to dryness - explosion and fire - temp exceds to quick and leaves explosion residues
-if pure - bp will be sharp
-if not then boil over a range

Question 4

measuring the bp of a sample

Answer 4

Set up the distillation apparatus with a thermometer that can measure up to 100°C.
Heat the sample until it boils.
Record the temperature at which the sample boils.
Compare the boiling point to the boiling point of the pure compound in a data booklet.

Question 5

prep of aspirin

Answer 5

reagents - salicylic acid, ethanoic anhydride, conc phosphoric or sulphuric
use water bath instead of beaker with hot water - control the temp easier as should not be allowed to rise over 65
avodi prolonged heating - avoid decomposing apsirin
-filter under pressure/ buchner - faster and solid is left dry - removes impurites and water pump reduces the pressure
-slow cyrstal over fast- fast can cause soluble impurities to become trapped in crystals
-encourage cyrstal formation - scratch on side of flask or put in ice cold water
-pour into water and stir before siltration - allow liquid to cyrstallise

Question 6

purify aspirin

Answer 6

-dissolve in min vol of hot solvent - as solution cools the sold can crystalisse out and leave behind impurities - avoid loss of products
-ensure bp does not exceed 78 - bp of ethanol is 78 and so would evaop
-cool solids using ice - increase yield of crystals

Question 7

what will impurities on mp

Answer 7

-lower it and would melt over several degrees

Question 8

anaylse the effectiveness of aspirin method

Answer 8

-loss of yield - cyrstals are lost during filtration or washing process- other sidde reactions - some products stay in solution

Question 9

why is ethanoyl chloride not used as much as ethanoic anhydride

Answer 9

-more expensive
-produces harmful HCl fumes