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Quiz4 - AnswerKey Chemistry223 PostlabQuiz 1...

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Answer Key Chemistry 223 Quantitative Analysis Laboratory Post lab Quiz 9/24/10 1. Drying ensured that you could accurately weigh your KHP and your acid unknown. Why couldn't the same procedure be used to make up a standard NaOH solution by drying solid NaOH, accurately weighing it, and dissolving it in water to avoid needing to do a KHP standardization? First, NaOH absorbs CO 2 , so the temperature would have to be high enough to decompose bicarbonate and carbonate into Na 2 O. That would also dehydrate NaOH into Na 2 O. This compound is even more hygroscopic than NaOH (Na 2 O + H 2 O gives 2 NaOH). Second, Na 2 O could also soak up CO 2 from the air and directly form Na 2 CO 3 . Thus, drying is insufficient to generate a stable, weighable compound. One would have to store Na 2 O in vacuum and weigh it in vacuum to use it as a primary standard 2. It's time to do a titration with NaOH. You obtain a buret, and find there is water clinging to the inside. You don't want that water to dilute your solution, and you realize that clinging drops are an
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