Which of the following dissolve in NaHCO3? benzyl alcohol, benzoic acid, or methyl benzoate.?

Question

Also why do only one of these dissolve? what are the chemical equations? What would be the reaction of the dissolved sample with HCl?

Any input would be greatly appreciated
thanks a lot

Answer 1

Presuming that NaHCO3 means an aqueous solution of NaHCO3, Benzyl Alcohol and Benzoic acid are likely to dissolve while Methyl Benzoate shall not. Benzyl alcohol shall dissolve to some extent due to the water in the aq. solun. while Benzoic acid shall dissolve through formation of its sodium salt. Further, Methyl benzoate may dissolve if the solun. is boiled (due to hydrolysis of the methyl benzoate into methyl alcohol and benzoic acid).

Answer 2

Only benzoic acid will dissolve, with a small abount of fizzing. This is a standard test to distinguish benzoic acid from phenol:
C6H5COOOH + NaHCO3 ------> C6H5COONa + CO2 + H2O

The other two are not acidic enough to dissolve, and their Mr is too high for any effective hydrogen bonding to overcome the hydrophobic nature of the benzene ring.

Adding HCl will produce a white precipitate of benzoic acid:

C6H5COONa + HCl -------> C6H5COOH + NaCl

Many, many students on carrying out this reaction assume that they have got an insoluble chloride, but it's not - it's an insoluble acid.

Answer 3

The reaction is normally 1:1, so the required amount of MeOH is only 0.025 mol (2.5 mmol). But you have 170 mmoles. So it is 170/2.5 = 68 times greater than required. good luck.