phenolphthalein were added and then it was titrated 3.54 mL of 0.048 M standardized NaOH to the endpoint. Method 2 – pH STRIP: You took 1 mL of the sample and used a pH strip to estimate the pH, which turned out to be around 3.3. Another 1 mL of the sample was diluted with 9 mL of water. The pH was taken again and is now around 3.8 d) Based on your answer in a) and c), do you think the unknown is really a strong acid or is it a weak acid instead? Defend your answer in one sentence. e) Rationalize the two pH readings in the pH strip test before and after dilution. Is this to be expected?
In Experiment 4, we used titration to determine the total acid content of samples, which we reported in terms of molarity. Reporting acidity through pH measurements is quite different, in that we can only measure the amount of the acid in its ionized form. You were tasked to investigate a clear aqueous solution of an unknown
monoprotic acid. You decided to use two Chem 16.1 methods to gather data.
Method 1 – TITRATION: A 10. mL aliquot of the sample was diluted with 25 mL distilled water. Two drops of phenolphthalein were added and then it was titrated 3.54 mL of 0.048 M standardized NaOH to the endpoint.
Method 2 – pH STRIP: You took 1 mL of the sample and used a pH strip to estimate the pH, which turned out to be around 3.3. Another 1 mL of the sample was diluted with 9 mL of water. The pH was taken again and is now around 3.8
d) Based on your answer in a) and c), do you think the unknown is really a strong acid or is it a weak acid instead? Defend your answer in one sentence.
e) Rationalize the two pH readings in the pH strip test before and after dilution. Is this to be expected?
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