Chemistry: Prduction or Benzoic acid

step 1: Mixing reactants

react measured volume of Benzyl methanol with excess saturated KMnO4 to ensure full oxidation of Benzyl methanol
add Na2CO3 to create alkaline conditions to speed up the recation

step 2: First reaction

heat in water bath at 60C for 20 minutes
an almond liek smell will be formed due to teh formation of teh intermediate compound Benzaldehyde
solution turen from purple to a brown percipitate as MnO4 turns into MnO2

step 3: HCl

cool flask under tap
add conc HCl:
neutralise Na2CO3
neutralise KOH
provides acidic conditions for reaction with sodium sulphite to produce Mn2+

step4: sulphite and ice bath

dip gloss rod into solution and then onto blue litmus paper to ensure all Na2CO3 and KOH are gone, litmus paper turns red
add saturated Na2SO3 
sulphite reduces MnO2 into soluble and colourless Mn2+
percipitate of white crystals of benzoic acid forms as it cools
put in ice bath to speed up and maximise the yield

purifying benzoic acid by recrystalisation

dissolve minimum of hot water to maximise yield
filter in hot apparatus to remove insoluble impurities (MnO2) and prevent premature crystalisation
fool filtrate to recrystalise
filter again to trap pure crsytals and remove impurities (KOH, NaCl)
wash crystals with ice cold water to remove last traces of impuities
dry crystals above radiator

melting point determination

place sample on aliminium block
heat slowlynot temp at which it begins to melt
note temp at which it all melted
melts over several degrees = impure
melts sharply (over 1 degree) = pure