Titration-sources of error

Titration as you already know is a very accurate procedure in measuring volume of liquids. However, because it is so sensitive and accurate many errors can occur throughout the procedure to give erroneous results. One very common source of error is contaminated glassware (pipette, burette). Contamination doesn't always come in the form of chemicals, water is a contaminant in the titration procedure because it acts to dilute our solutions.
Since you are familiar with the titration procedure, complete the table below.
20ml aliquots(samples of the unknown) of an unknown acid solution were titrated each time with base. The average titre (volume of base solution added from the burette) is given for a normal, error free titration. Indicate wether the average titre will be lower or higher than the normal.
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Source of error

Average titre (mls)

Error free titration


Water in the pipette

> 33.45,< 33.45 or = 33.45

Water in the burette

> 33.45,< 33.45 or = 33.45

> 33.45,< 33.45 or = 33.45

Acid in the burette

> 33.45,< 33.45 or = 33.45

Acid solution in the flask

> 33.45,< 33.45 or = 33.45