A student plans a series of chemical tests to confirm the identities of four organic liquids: P, Q, R, and S.
This is the student's method.
To separate test tubes containing samples of each liquid:
- Test 1: add Fehling's solution and cool in iced water
- Test 2: add sodium hydrogencarbonate solution and test any gas produced with a burning splint
- Test 3: add potassium dichromate(VI) solution and warm gently
- Test 4: add bromine water and shake at room temperature
a.[1]
Identify the missing reagent needed in Test 3.
b.[4]
In addition to the missing reagent in Test 3, there is a mistake in the method for two of the other tests. State the two mistakes and suggest how each should be corrected.
c.[8]
The missing reagent is added and the mistakes are corrected. Identify the liquid(s), P, Q, R, and S, that would react in each test and state the expected observation for each reaction.