Question

5. Calculate the pH of a 0.04 M HCl solution. Compare to the pH found in problem 4 Note: this is not a buffer! 6. What properties of a buffer solution provides for a solution with a higher capacity to withstand changes in pH? Provide at least 3.

Answer 1

1. Hel is a strong acid, so it dissociates completely to give ions in the solution. or g Hal - H+ + - 0.04 0.04M Ch+] 20.04 M- mo . - pH = - wg ([nt]) - Log (604) PH = 1 Ao 3. ph of 0.04m hd is 1.40 I NOTE : question - 3 is not provided. so can not compare determined by the ③. PH of a buffer solution is Handerson equation at pt = [salt] pri = pka & log pka & log Thu = -log (ka)&log [A-]. the So, pH of buffer solution depends on on two main factors - ( dissociation constant of acid (ka). THAJ Now, for a butter solution ka is fixed. b IHAJ changes (1) Now a strong acid is added to the system which is completely dissociate in the solution to give H C A 0.1 He can change the pH of the solution by 1 as - rog (H) = -log (oil) - 1). But in the buffer solution reacts with the salt (A) to give same amount of HA so the log ratio of ra] and [HAJ becomes significantly lower than the 1. So, PH changes occur to a wtle amount

( When strong base Crike Noor) is added to plot the system i the one comes from the strong base reacts with the HA to form H2o and and conjugate base (4-). HA & ot 20 TAO. Thus direct effect of one is reduced. rather 7 change which effect the pH of the buffer solution slightly af log [AT THAJ (3) Generally buffer solution is prepared by equal concentration of acid and bits conjugate base. This is due to the fact that the buffer solution has equal resistance towards acid and base. (4) In buffer solution wear acid is used. weak. acid dissociates in the solution to a very less extent. Again dissociation is prevented by the common ion (A ) Present in the solution. Thus pH of solution changes to a very less extent. By these ways we can explain ага bu see solution. -- the buffer capasity . . eur LA boxit Nortolot y et boibo Noi wo Salomon 90 - = -=-