Required practical 5b Flashcards
Step 1
Make the oxidising agent by dissolving potassium dichromate in dilute sulfuric acid
What should the concentration of the oxidising agent be
1 gram per 10cm3
Step 2
Using a 25cm3 measuring cylinder, carefully measure 12cm3 of the oxidising agent into boiling tube
Step 3
Cool the boiling tube in a beaker of cold water
Why should the boiling tube be kept cool
To avoid the loss of volatile ethanal
Step 4
Using a 10cm3 measuring cylinder, carefully measure 2cm3 ethanol into a test tube
Step 5
Using a teat pipette, slowly add the 2cm3 ethanol to the oxidising agent in the cooled boiling tube
What is essential when adding the ethanol
Shaking the tube gently to mix the contents
Step 6
Add a few anti bumping granules and attach a bung fitted with a right angled glass delivery tube
What is the role of anti bumping granules
Prevent the formation of large bubbles
Step 7
Clamp the boiling tube at 45 degrees in a baker of water so that the delivery tube goes to a test tube which is immersed in cold water in a beaker
Step 8
Gently heat the mixture to slowly distil approximately 5cm3 of liquid distillate
What method is used to test for the presence of an aldehyde
Tollen’s
Tollens - step 1
Add 5cm3 NaOH to 2cm3 silver nitrate in a test tubet
Tollens - step 2
Add just enough dilute ammonia to completely dissolve the brown precipitate
