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Purpose
To determine the equivalence points of two titrations from plots of pH versus mL of titrant added.
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Goals
1. To gain experience performing acid-base titrations with a pH meter. 2. To plot titration curves of pH vs mL of titrant added. 3. To determine the equivalence point of a titration from a titration curve. 4. To determine the pKa of an analyte from a titration curve.
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Introduction
A titration is an analytical procedure in which a reaction is run under carefully controlled conditions. The stoichiometric volume of one reactant of known concentration, the titrant, that is required to react with another reactant of unknown concentration, the analyte, is measured. ...
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Equipment
1 MicroLab Interface, 1 MicroLab pH Measurement Instruction Sheet, 1 pH electrode in pH 7.00 buffer, 2 30 mL beakers, 2 50 mL beakers, 1 250 mL beaker, 1 100 mL graduated cylinder, 1 20.00 mL volumetric pipet, 1 pipet bulb, 1 magnetic stir plate, 1 magnetic stir bar, 1 25 mL buret, 1 ring stand ...
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Reagents
~25 mL 0.20 M potassium hydrogen phthalate (KHP), ~30 mL
0.20 M sodium hydroxide (NaOH), 3 drops phenolphthalein solution, ~25 mL
0.10 M sodium carbonate (Na2CO3), ~30 mL 0.20 M hydrochloric acid (HCl), 3 drops methyl orange solution, ~15 mL
pH 4.00 buffer, ...
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Lab Procedure
In this experiment, you will be using pH electrodes connected to the MicroLab Interface. pH electrodes have a thin glass bulb at the tip. They break easily and are costly to replace. Be careful not to shove the electrode into the bottom of a beaker or drop the electrode. ...
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Worksheet
You will use a hard copy of this worksheet to enter data as you work through the experiment in lab. Print the worksheet and bring it with you to the lab...