Question

I need help with #3, 4. Also, I am confused with #5 because both pH are the same.

Ka 1-7X10 4 3. In a titration between HCHO, and KOH, would the pH at the equivalence point be acidic, basic, or neutral? Briefly explain your answer. HCHO+KOH b) Which of the following acid-base indicators would be the best one to use in the titration? i) methyl orange, Ka = 104 ii) bromthymol blue, Ka = 10-7 iii) thymolphthalein, Ka= 10-10

Answer 1

3. In the titration of HCHO, and KOH Нcook4 ама као и и bе fомил Х. Now Hoot is a meak auld whereas KOH is a strong base. Tun Tue confugante base of 4coot will accept proton to come back to its initial state. This at equivalance point [04] will be higher. Thus, equivalance point will be basic 6 Now the indicator having pka greater tham 7 will be suitable for the above titration. 1 Methyl orange apka= -log (104) = 4 4) bromthymol blue, pka = -7)=7 on) thymolph thalein , pka = -log (10-10 = 10. Thus, thymool phthalein neill be suitable for this titration 4 we know buffer solution means, if we all base to a acid buffer solution, repto certain amount of base, the pH will not Change. Thus, bubleer capacity is the efficiency of a buffer in resisting a change in ph. It is defined by B. Mainity buftes capacity is in the range of PHI 1

classmate Date Page 5 a) pk.ba -log (1:40x100 = 8.85 Now, buffer_ pH of buic buffer, re:47 I PH2 pkb - log Base] 2152 = 8.85 - log 3.48 T 28.99. 6 After addition of 150 ml 3:16Mther to the I buffer solution homenç roleume 875 ml II Base 7= 8 75 x 3.48-150x316 875+ 150 L = 2:50 M. cong agence Achel Conjugate Acid) 875x2.52 +150 X 316 875+150 2.GIM. pta pkg-log Consugate and Ha eke Base ta 8.85 - log 2.61 2.50 = 8.83