Question

Rank the following solutions in order of increasing acidity.

1 M phenol
1 M boric acid
1 M cyanic acid
1 M formic acid
1 M hydrochloric acid

2. Rank the following solutions in order of increasing basicity.

1 M C3H5O3Na
1 M KF
1 M KOCN
1 M KOCl

All I know is that HCl is the strongest acid. I'm really lost and would appreciate some urgent help.

Answer 1

You're right. HCl is the strongest acid. Note that all of the other acids are weak and have a Ka. Look in your text for Ka for each. Then rank the Ka values from weak to strong. The smallest Ka will be the weakest acid.

#2. All of these are salts and K^+ is not hydrolyzed. The anion of each is hydrolyzed. Kb for each anion = Kw/Ka where H2 = 1E-14 and Ka is the Ka for the corresponding acid; e.g., KOCl is HOCl for Ka, KOCN is HOCN for Ka, etc. The value of Kb (Kw/Ka) will give you the relative strengths. Note that all anions give the weak acid + OH^- upon hydrolysis.