Consider the titration of 20.00mL of HCl(aq) with M=.400M by,80DM KOH(aq) Determ
ID: 1005508 • Letter: C
Question
Consider the titration of 20.00mL of HCl(aq) with M=.400M by,80DM KOH(aq) Determine the ph of the mixture before the addition of any OH' A) 1.000. B) 0.398 C) 0.300 D) Need the K_a of the hall determine the ph after the addition of 5.00mL OH' A) 1.301 B) 0.796 C)1 0.495 D) 4.301 Determine the mL KOH Needed at the equivalence pt, and the pH upon the addition of this volume of KOH. A) 10.0, 7.00 B) 20.0, 7.00 C) 10.0,14.00. D) 20.0/3.50 Determine the ph after the addition of 20.00mL OH". A) 0.70 10.699 C) 11.85' D)'13.30Explanation / Answer
Titration of HCl by KOH
a) Before addition of KOH
pH = -log(0.4) = 0.398
Answer : b) 0.398
b) After 5 ml KOH added
pH = -log[(0.4 M x 20 ml - 0.8 M x 5 ml)/25 ml] = 0.796
Answer : b) 0.796
c) Volume of KOH at equivalence point = 0.4 M x 20 ml/0.8 M = 10 ml
pH at equivalence point = 7
Answer : A) 10.0, 7.0
d) After 20 ml KOH added
excess [OH-] = (0.8 M x 20 ml - 0.4 M x 20 ml)/40 ml = 0.2 M
pOH = -log[OH-] = 0.699
pH = 14 - pOH = 13.30
Answer : D) 13.30