[woned707]

Hi there,

I am writing this to request for help to find answers/websites that can give good answers to
i) why sodium carbonate is put in small quantity before the start of the experiment with hydrochloric acid.   
ii) What are the two major sources of errors to collecting the product of NA₂CO₃ and HCl, i.e. CO2 over displacement of water.
iii) once identify the sources of errors, what are the method for reducing this error and what is the explanation of the method reducing it.

I would really appreciate some help as soon as possible as I am helping to tutor some students in preparation for their exams.  Thank you.  ^_^