Question
For equal volumes of \({\text{1.0 mol}}\,{\text{d}}{{\text{m}}^{ – 3}}\) solutions of hydrochloric acid, HCl(aq), and methanoic acid, HCOOH(aq), which statements are correct?
I. HCl dissociates more than HCOOH
II. HCl is a better electrical conductor than HCOOH
III. HCl will neutralize more NaOH than HCOOH
A. I and II only
B. I and III only
C. II and III only
D. I, II and III
▶️Answer/Explanation
A
HCl is strong acid and HCOOH is a weak acid. HCl dissociates more than HCOOH and it is a better electrical conductor than HCOOH.
Both strong acids and weak acids require equal moles of alkali for neutralization.
Question
When equal volumes of four \({\text{0.1 mol}}\,{\text{d}}{{\text{m}}^{ – 3}}\) solutions are arranged in order of increasing pH (lowest pH first), what is the correct order?
A. \({\text{C}}{{\text{H}}_{\text{3}}}{\text{COOH}} < {\text{HN}}{{\text{O}}_{\text{3}}} < {\text{C}}{{\text{H}}_{\text{3}}}{\text{C}}{{\text{H}}_{\text{2}}}{\text{N}}{{\text{H}}_{\text{2}}} < {\text{KOH}}\)
B. \({\text{HN}}{{\text{O}}_{\text{3}}} < {\text{C}}{{\text{H}}_{\text{3}}}{\text{COOH}} < {\text{C}}{{\text{H}}_{\text{3}}}{\text{C}}{{\text{H}}_{\text{2}}}{\text{N}}{{\text{H}}_{\text{2}}} < {\text{KOH}}\)
C. \({\text{C}}{{\text{H}}_{\text{3}}}{\text{C}}{{\text{H}}_{\text{2}}}{\text{N}}{{\text{H}}_{\text{2}}} < {\text{HN}}{{\text{O}}_{\text{3}}} < {\text{C}}{{\text{H}}_{\text{3}}}{\text{COOH}} < {\text{KOH}}\)
D. \({\text{KOH}} < {\text{C}}{{\text{H}}_{\text{3}}}{\text{C}}{{\text{H}}_{\text{2}}}{\text{N}}{{\text{H}}_{\text{2}}} < {\text{C}}{{\text{H}}_{\text{3}}}{\text{COOH}} < {\text{HN}}{{\text{O}}_{\text{3}}}\)
▶️Answer/Explanation
B
KOH is a strong base, it has highest pH. {\text{C}}{{\text{H}}_{\text{3}}}{\text{C}}{{\text{H}}_{\text{2}}}{\text{N}}{{\text{H}}_{\text{2}}} is weaker base it has second highest pH. {\text{C}}{{\text{H}}_{\text{3}}}{\text{COOH}} is a weak acid, it has third highest pH and \({\text{HN}}{{\text{O}}_{\text{3}}} being strong acid will have lowest pH.
Question
Which list contains only strong acids?
A. \({\text{C}}{{\text{H}}_{\text{3}}}{\text{COOH, }}{{\text{H}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}{\text{, }}{{\text{H}}_{\text{3}}}{\text{P}}{{\text{O}}_{\text{4}}}\)
B. \({\text{HCl, HN}}{{\text{O}}_{\text{3}}}{\text{, }}{{\text{H}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}\)
C. \({\text{C}}{{\text{H}}_{\text{3}}}{\text{COOH, HN}}{{\text{O}}_{\text{3}}}{\text{, }}{{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}}\)
D. \({\text{HCl, HN}}{{\text{O}}_{\text{3}}}{\text{, }}{{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}}\)
▶️Answer/Explanation
D
\({\text{HCl, HN}}{{\text{O}}_{\text{3}}}{\text{, }}{{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}}\) are strong acids.
\({\text{C}}{{\text{H}}_{\text{3}}}{\text{COOH, }}{{\text{H}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}{\text{, }}{{\text{H}}_{\text{3}}}{\text{P}}{{\text{O}}_{\text{4}}}\) are weak acids.
Question
Which of the following are weak acids in aqueous solution?
I. \({\text{C}}{{\text{H}}_{\text{3}}}{\text{COOH}}\)
II. \({{\text{H}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}\)
III. HCl
A. I and II only
B. I and III only
C. II and III only
D. I, II and III
▶️Answer/Explanation
A
Weak acids are acids that do not entirely ionize in solution or have a low concentration of the ion. Example-Oxalic acid, Acetic acid, Carbonic acid.
Strong acids are those that ionize entirely in solution or have a large concentration of the ion. Example-Sulfuric acid, Hydrochloric acid.
\({\text{C}}{{\text{H}}_{\text{3}}}{\text{COOH}}\) and \({{\text{H}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}\) are weak acids as do not entirely ionize in solution or have a low concentration of the ion.
Question
An example of a strong acid solution is perchloric acid, \({\text{HCl}}{{\text{O}}_{\text{4}}}\), in water. Which statement is correct for this solution?
A. \({\text{HCl}}{{\text{O}}_{\text{4}}}\) is completely dissociated in the solution.
B. \({\text{HCl}}{{\text{O}}_{\text{4}}}\) exists mainly as molecules in the solution.
C. The solution reacts only with strong bases.
D. The solution has a pH value greater than 7.
▶️Answer/Explanation
A
Strong acid releases H+ in water and is completely dissociated in the solution.
\({\text{HCl}}{{\text{O}}_{\text{4}}}\) will form H+ and ClO4– ions.
Strong acids can react with weak bases also.
The solution would be acidic and have a pH value less than 7.