Ch23 Experiments Flashcards
Lard is a source of
Long chained esters
Ethanol is a
Solvent to mix the solids
Anti numbing chips are added
To help boiling to take place more smoothly
Reflux
Hot vapours of liquid rise and enter Liebig condenser
Vapours are cooked back to liquid
Drops of liquid fall back into flask
Purpose of reflux
Allows time for the reaction to complete
Reaction to be boiled without losing volatile material
Allows yield to be maximised
After heated what can be seen?
Coating of sodium salts on inside of flask
Flask is heated gently what is distilled ?
Ethanol
Removal of ethanol makes
It easier to isolate the soap
So soap is not contaminated with ethanol
Residue was poured
Into small amount of boiling water and then poured into brine
Why brine ?
Soap does not dissolve in salt solution and therefore is precipitated
Excess sodium hydroxide dissolves
Filter soap
Wash in more bribe
Dry soap in an oven
What is the making of soap called
Base hydrolysis of an ester
Saponification
Reaction of ethanal with acidified potassium permanganate
- add dilute potassium permanganate
- add ethanal
- HEAT
- purple goes to colourless
Doesn’t work with propanone- ketones are not oxidised
_ + _ 2+
MnO4 +8H +5e–> Mn +4H2O
Reaction of ethanal with fehlings reagent
-mix equal amounts of fehlings A+B
-add ethanal
-HEAT
-CLEAR Royal blue= fehlings solution
-brick red ppt when heated with ethanal
-propanone doesn’t work-ketones are not oxidised
2+ _ +
Cu +e —> Cu
Blue Red
Reaction of ethanal with ammoniacal silver nitrate
-tokens reagent is made with nitrate solution dilute sodium hydroxide and dilute ammonia solution (explosive so made fresh)
-tollens reagent added to test tube of ethanal
-HEAT water bath
-silver mirror formed
+ _
Ag + e —>Ag silver ppt
