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1001 MCAT Chemistry- Question 847 and 853
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umghai
#1 Posted : Wednesday, July 20, 2011 1:47:24 AM
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For question 847, I thought the answer would be 60 mL because the reaction has two equivalent points.

For question 853, I thought the answer would be 0 M, 0 M, and 0.1 M. When you reach the equivalent point, it corresponds to the concentration of the unknown acid. In this case, we know the initial concentration, so it would be 0.1 M.

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selenahuang
#2 Posted : Wednesday, July 20, 2011 9:18:47 PM
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847) In a titration, the amount of acid doesn't depend on the number of steps that fully deprotonate the polyprotic acid. The whole amount of H2CO3 has been converted to HCO3- at the first equivalence point. As a result, the first equivalence point is the one to be used to calculate the amount of H2CO3

853) At the second equivalence point, not only all the acid as been converted to CO2(2-), but you also have added 60ml of water to the solution, hence the concentration is diluted
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