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H-6
Remember that the mass of each acid sample must be accurately determined on an analytical
balance. Add the base quickly until the equivalence point is nearly reached. Then, proceed to add
the base dropwise for the rest of the titration until the indicator changes color on one drop of
titrant. In these last two or three titrations try to obtain values for the molar mass of the unknown
acid that agree within one or two percent. If your results are good, two titrations with the correct
indicator should be sufficient. If not, you may wish to do a third titration. It is important to work
quickly, but accurately. If you do not, you may not be allowed to finish all the titrations you need
to perform.
Before leaving the laboratory, check to make sure that all of your equipment is clean and back in
your drawer. It is important that the pH electrode has been washed and is stored in storage buffer
of pH 4.
When you have finished all of your titrations, and have disposed of all of the wastes properly,
wash your burets with hot
tap water (four times) and rinse once with deionized water. Leave
them at your work station filled with deionized water.
