Question

Caclulate the pH of:

a 0.200 M solution of NaCH3COO

a 0.200 M solution of NH4NO3

a 0.200 M solution of NaCl

CH3COOH 1.76 * 10^-3

NH4⁺ 5.68 * 10^-10

HCl >1

Predict whether the following would be acidic, basic, or neutral in solution:

0.5 M NaCN

0.5 M KCl

0.5 M Ba(NO₃)₂

0.5 M NH₄C₂H₃O₂

Answer 1

I)

a) 0.200 M solution of NaCH3COO

since the salt is made up of weak acid and strong base the resultant solution will be basic in nature

C=0.200M

Ka of CH3COOH 1.76 * 10^-3

pH=7 +1/2(pKa + logC)

pH=7+1/2(-log(1.76*10^-3)+log(0.2))=8.03

b)0.200 M solution of NH4NO3

since the salt is made up of strong acid and weak base the resulting solution will be acidic

pH=7-1/2(pKb+logC)

pH=7-1/2((-log(5.68 * 10^-10)+log(0.2))=2.7

c) since the salt is made up of strong acid and strong base so the resulting solution will be neutral

therefore the pH valueis 7

II)

0.5 M NaCN :basic

0.5 M KCl : neutral

0.5 M Ba(NO₃)₂ :neutral

0.5 M NH₄C₂H₃O₂ neutral(it is a salt of weak acid and weak base)