Concept explainers
Strong Acids, Weak Acids, and pH
Two 0.10-mol samples of the hypothetical monoprotic acids HA(aq) and HB(aq) are used to prepare 1.0-L stock solutions of each acid.
- a Write the
chemical reactions for these acids in water. What are the concentrations of the two acid solutions? - b One of these acids is a strong acid, and one is weak. What could you measure that would tell you which acid was strong and which was weak?
- c Say that the HA(aq) solution has a pH of 3.7. Is this the stronger of the two acids? How did you arrive at your answer?
- d What is the concentration of A−(aq) in the HA solution described in part c?
- e If HB(aq) is a strong acid, what is the hydronium-ion concentration?
- f In the solution of HB(aq), which of the following would you expect to be in the greatest concentration: H3O+(aq), B−(aq), HB(aq), or OH−(aq)? How did you decide?
- g In the solution of HA(aq), which of the following would you expect to be in the greatest concentration: H3O+(aq), A+(aq), HA(aq), or OH−(aq)? How did you decide?
- h Say you add 1.0 L of pure water to a solution of HB. Would this water addition make the solution more acidic, make it less acidic, or not change the acidity of the original solution? Be sure to fully justify your answer.
- i You prepare a 1.0-L solution of HA. You then take a 200-mL sample of this solution and place it into a separate container. Would this 200 mL sample be more acidic, be less acidic, or have the same acidity as the original 1.0-L solution of HA(aq)? Be sure to support your answer.
Interpretation:
The explanations for the given set of statements have to be given.
Concept introduction:
Acid:
According to Bronsted-Lowry theory, a species which donates a proton in a proton transfer-reaction is said to be an acid.
Base:
According to Bronsted-Lowry theory, a species which accepts a proton in a proton transfer-reaction is said to be base.
Answer to Problem 15.20QP
(a)
The concentration for the two solutions is
The chemical equations for the given reactions are
(b)
The
(c)
The given solution is weaker of the two acids.
(d)
The concentration of
(e)
The concentration of hydronium ion is
(f)
The greatest concentration must be for
(g)
The greatest concentration must be for
(h)
The
(i)
The given solution has the same
Explanation of Solution
(a)
The concentration for the two solutions is
The chemical equations for the given reactions are
(b)
By measuring the
(c)
The given solution is weaker of the two acids. Why because the strong acid has
(d)
The concentration of
Hence, the concentration of
(e)
The concentration of hydronium ion is
(f)
The greatest concentration must be for
(g)
The greatest concentration must be for
(h)
The
(i)
The given solution has the same
The explanations for the given set of statements were given.
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Chapter 15 Solutions
General Chemistry
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