Titration Lab

(Do not print out!)

 Mission:  Find the molarity of 3 unknown acids using a known base.

Background:  The concentrations of acids and bases are expressed in molarity which is the moles of acid or base divided by the liters of solution.  Since acids and bases neutralize each other when mixed, a known sample of one can be used to determine an unknown concentration.  When the amount of the known sample reacts with the exact amount of unknown to neutralize it, the measurements of volume will allow the calculation of the unknown molarity.  Indicators are used to determine the precise point where your sample changes from acid to base.

Procedure:   Set up a burette for titration.  Add base of known concentration and read the volume.  Get a sample of acid of about 5 to 10 ml. acid in a beaker.  Add a few drops of indicator.  Slowly release base from the burette into the beaker until the indicator changes color. Record the level in the burette.  Use the values measured to calculate the unknown acid molarity.

Data:  Set up a data table and record the following for each titration – the beginning volume of the base in the burette, the final value, the amount of base used, the volume of the acid sample.  Calculate the moles of base for each titration and find the corresponding number of moles of acid.  Find the molarity of the acid.

 Your table might look like this (but make your own!)

Molarity of known Base = ________

Analysis:  Determine the molarities of the acid samples and show your calculations.  Write a conclusion.

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