Preparation of Benzoic Acid Flashcards
1
Q
Why is an excess of potassium manganate used?
A
To ensure complete oxidation of the alcohol to the acid
2
Q
Identify the brown precipitate formed
A
Mn4+
3
Q
Give two reasons why the solution was acidified with concentrated hydrochloric acid
A
Convert sodium benzoate to benzoic acid
Neutralise any bases
Provide conditions to enable Mn4+ to be reduced to soluble Mn2+
4
Q
What reaction occured when the sodium sulfite was added?
A
Reduced Mn4+ to Mn2+
5
Q
Why was the flask placed in ice before filtration?
A
To ensure all benzoic acid crystallises out of solution
6
Q
Describe the appearance of phenylmethanol at room temperature
A
Colourless oily liquid
7
Q
What changes occur after adding hydrochloric acid and sodium sulfite
A
Brown precipitate dissolves
White crystals form
