Standard_NaOH_StudentLab

Standard_NaOH_StudentLab - Acid-Base Chemistry...

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Acid-Base Chemistry Standardization of a NaOH Solution For the next few labs, you will need a standardized solution of NaOH. In this experiment, you will be standardizing (determining the molarity) of the base solution. The accuracy of these analyses will depend on the care you use in doing this experiment. Titrations can be done very precisely and accurately. You should strive for both in your work. You will determine the concentration of your NaOH solution by using it to titrate an accurately massed sample of a solid acid, potassium hydrogen phthalate (abbreviated KHP ). This process is called standardization , and the KHP is referred to as the primary standard . Primary standard substances must have certain properties. They should be available in a state of known purity, should be easy to dry and should not pick up moisture from the air, and should have a high molar mass. There are several good primary standard acids. We will be using KHP which is available in purity of 99.95% or better, is easily dried and stable at 110 o C, and has a molar mass of 204.22 g/mole. Only one of its hydrogens has acidic properties (ionizes), therefore one mole of KHP will exactly neutralize one mole of NaOH. Equipment and Chemicals: solid KHP two 250-ml Erlenmeyer flasks 250-ml beaker 50-ml buret NaOH solution - approx. 0 . 1 M buret clamp and ring stand buret funnel 1% mass/volume phenolphthalein in C 2 H 5 OH indicator solution Procedure: 1. Samples of dry KHP are available in the drying ovens. Mass out approximately 0.5 - 0.8 grams. This sample must be massed accurately so you will be massing by difference. Mass the plastic container holding the KHP, measuring to milligram accuracy on the top-loader balances. Remove a small sample and put this sample directly into a 250-ml Erlenmeyer flask. Remass the plastic container. The mass
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Standard_NaOH_StudentLab - Acid-Base Chemistry...

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