lab 7 - 20 mL of DI-water. Add 3 drops of phenolphthalein...

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Purpose: To standardize a sodium hydroxide to determine the molarity by using the primary acid standard, KHP To identify and standardize NaOH solution to determine the molar mass of an unknown acid sample Procedure: Part A: Standardization of NaOH Obtain a buret and a 500mL volumetric flask. Weight 3.014 grams of NaOH on a top loading balance and dissolve it in 500 mL of DI-water in a volumetric flask. Set up the buret in the buret stand and place a waste beaker under the buret. Fill the buret with DI-water with the stopcock closed and allow the water in the buret to drain into the waste beaker. Fill the buret with a rinsing solution of NaOH and allow the solution in the buret to drain into the waste basket. Transfer the NaOH solution from the flask into the buret using a funnel above the 0.00 mL mark. Carefully open the stopcock and allow the solution level to drop to 0.00 mL mark. Weigh out 0.5-0.6 g of KHP on the top loader balance, then re-weigh it accurately on the analytical balance. Transfer the solute into the Erlenmeyer flask by adding
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Unformatted text preview: 20 mL of DI-water. Add 3 drops of phenolphthalein indicator to the KHP solution in the Erlenmeyer flask. Check to see that there are no air bubbles in the tip of the buret. Open the stopcock to allow the NaOH solution to drip into the Erlenmeyer flask with constant swirling of the flask. Stop when the light pink color appears. Repeat steps 8-12 for three more trials. Part B: Molar Mass of an Unknown Acid Weight out .40-.55 g of unknown A on the top loading balance, then re-weight it accurately on the analytical balance. Transfer the solute into the Erlenmeyer flask by adding 20 mL of DI-water. Add 3 drops of phenolphthalein indicator to the unknown acid solution in the Erlenmeyer flask. Open the stop cock to allow the NaOH solution to drip into the Erlenmeyer flask with constant swirling of the flask. Stop when the light pink color appears. Repeat steps 13-16 for two more trials. Calculate the percent error....
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lab 7 - 20 mL of DI-water. Add 3 drops of phenolphthalein...

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