In: Chemistry
Determine the pH of each of the following solutions.
A) 2.00×10−2 M HClO4
B) 0.120 M HClO2
C) 3.5×10−2 M Sr(OH)2
D) 8.60×10−2 M KCN
E) 0.150 M NH4Cl
A) pH of strong acid (HClO4): pH = -log[H+] =
-log(2.00*10^-2) = 1.699
B) pH of weak acid(HClO2): pH = 1/2(pKb-log(C)) =
= 1/2(1.96-log(0.120)) = 1.44
c) pOH of Sr(OH)2(strong base): pOH = -log(OH-) =
-log(2*1.35*10^-2) = 1.569
pH of the solution =14 -pOH = 14-1.569 =
12.431
D) pH salt of strong base and weak acid (KCN) = 7+ 1/2(pKa +log(c))
= 7+1/2(-log(Ka)+log(C))
= 7+1/2(-log(4.0*10^-10)+log(8.60*10^-2)
= 11.166
E) pH salt of WEAK base and STRONG acid (NH4Cl) = 7- 1/2(pKb +log(c))
= 7-1/2(-log(Kb)+log(C))
= 7-1/2(-log(1.8*10^-5)+log(0.150))
= 5.03