C. Standardization of HCI titrant 1. Dry 1.5 to 2.0 g pure NazCOs in a glass weighing bottle at 150 to 160°C for at least 2h. Allow cooling in a desiccator. 2. Weigh 0.15 g (±0.3 mg) portions of the dry material into clean Erlenmeyer flasks. Do triplicate measurements. 3. Add about 50 mL of distilled water to each and swirl gently to dissolve the salt. 4. Add 4 drops of bromocresol green indicator and titrate with the HCI solution to an intermediate green color. 5. When the solution already turned into green, stop the titration and boil the solution gently for a minute or two, taking care that no solution is lost during the process. Cool the solution to room temperature, wash the flask walls with distilled water from wash bottle, and then continue the titration. Just before the end point, the titrant is best added in half drops (follow instructor's demonstration for the half-drop technique). 6. Record the burette reading. Use the indicator correction to compute the molarity of HCI. Note: Do not forget to subtract first the volume for the indicator correction.

C. Standardization of HCI titrant 1. Dry 1.5 to 2.0 g pure NazCOs in a glass weighing bottle at 150 to 160°C for at least 2h. Allow cooling in a desiccator. 2. Weigh 0.15 g (±0.3 mg) portions of the dry material into clean Erlenmeyer flasks. Do triplicate measurements. 3. Add about 50 mL of distilled water to each and swirl gently to dissolve the salt. 4. Add 4 drops of bromocresol green indicator and titrate with the HCI solution to an intermediate green color. 5. When the solution already turned into green, stop the titration and boil the solution gently for a minute or two, taking care that no solution is lost during the process. Cool the solution to room temperature, wash the flask walls with distilled water from wash bottle, and then continue the titration. Just before the end point, the titrant is best added in half drops (follow instructor's demonstration for the half-drop technique). 6. Record the burette reading. Use the indicator correction to compute the molarity of HCI. Note: Do not forget to subtract first the volume for the indicator correction.

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter13: Titrations In Analytical Chemistry

Section: Chapter Questions

Problem 13.28QAP

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