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This 1 page Class Notes was uploaded by Brianna Hinton on Friday October 14, 2016. The Class Notes belongs to 102 at University of North Carolina - Chapel Hill taught by Carribeth Bliem in Fall 2016. Since its upload, it has received 12 views. For similar materials see General Chemistry II in Chemistry at University of North Carolina - Chapel Hill.
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Date Created: 10/14/16
Friday, October 14, 2016 Gen Chem II Notes Titrations A known concentration of base (or acid) is slowly added to a solution of acid (or base). Titration of a Strong Acid with a Strong Base pH= 7.00 ex) HCl + NaOH → H O + NaCl 2 From the start of the titration to near the equivalence point, pH goes up slowly. Just before and after the equivalence point, the pH increases rapidly. At the equivalence point, moles acid= moles base, and the solution contains only water Titration of a Weak Acid with a Strong Base ● Unlike in the previous case, the conjugate base of the acid affects the pH when it is formed. ● If you have a weak acid and you put in NaOH, at the equivalence point, why is the pH greater than 7? I t is because you added a weak acid. This weak acid was converted into a weak base, the conjugate base. This reacts with the water - and makes a little hydroxide ion (OH ), making the pH greater than 7.00. ● At each point below the equivalence point, the pH of the solution during titration is determined from the amounts of the acid and its conjugate base present at that particular time. The buffer capacity is enough to buffer against large pH changes. Henderson-Hasselbach! Titration of a Weak Base with a Strong Acid The pH at the equivalence point in these titrations is < 7 due to presence of conjugate acid of weak base: + + HB + H2 ←> B + H3 At the equivalence point, you’ve created a salt solution.