posted by Amanda .
Please help !!!!
The acid impurity in your unknown was benzoic acid.
a) Write an equation for the reaction that occurs during the NaOH extraction.
b) Write an equation for the reaction that occurs after the addition of HCL. Thanks.
acid + base = salt + water
HBz + NaOH ==> NaBz + H2O
NaBz + HCl ==> HBz + NaCl
Benzoic acid is C6H5COOH and it is the right most H that is involved in the reaction. I have let Bz stand for C6H5COO.
The idea behind this is that benzoic acid reacts with NaOH to produce the sodium salt which is quite soluble in water. That allows you to separate the benzoic acid from the reactants in the procedure. After separation, you want to regenerate the benzoic acid so you add HCl and that re-precipitates the benzoic acid and you can extract that into an organic solvent.