AP Chemistry : Strong and Weak Acids and Bases

Study concepts, example questions & explanations for AP Chemistry

varsity tutors app store varsity tutors android store

Example Questions

Example Question #66 : Acid Base Reactions

Which of the following is a strong acid?

Possible Answers:

Lactic acid

Acetic acid

Hydroflouric acid

Formic acid

Nitric acid

Correct answer:

Nitric acid

Explanation:

This question is simply testing your memorization of strong and weak acids. Of the list, you should recognize that nitric acid is the only strong acid, and the rest of the choices are weak. 

Example Question #1 : Strong And Weak Acids And Bases

Which of the following is what determines the strength of an acid?

Possible Answers:

The Kb

Its physical state

How many bonds the central atom makes

Electronegativity values

The Ka

Correct answer:

The Ka

Explanation:

The Ka is the acid dissociation constant, and thus it is what determines how strong the acid is. Stronger acids dissociate to a greater extent and produce lower pH values.

Example Question #2 : Strong And Weak Acids And Bases

A 1M solution of a monoprotic acid has a pH of 4.6. What is the  value for the conjugate base of the acid?

Possible Answers:

Correct answer:

Explanation:

In order to find the base dissociation constant for the conjugate base, we can start by finding the acid dissociation constant for the acid. Since a 1M solution of the acid has a pH of 4.6, we can find the proton concentration of the solution.

Since the acid is monoprotic, we can set the following equilibrium expression equal to its acid dissociation constant.

We can see that, since the acid is monoprotic, the concntration of protons will be equal to the concentration of the acid anion. The final concentration of the acid molecule will be equal to the initial concentration, minus the amount of protons formed. Using these values, we can solve for the equilibrium constant for the acid.

Now that we have the acid dissociation constant, we can find the conjugate base's dissociation constant by setting the product of the two values equal to the autoionization of water.

Example Question #2 : Strong And Weak Acids And Bases

Would H2SO4 or HNO3 produce a more acidic solution?

Possible Answers:

H2SO4 since it has a lower pKa

HNO3 since it has a lower pKa

HNO3 since it has a higher pKa

H2SO4 since it has a higher pKa

Correct answer:

H2SO4 since it has a lower pKa

Explanation:

Both are strong acids, but H2SO4 is bivalent, realeasing 2 protons for each molecule dissolved in solution. Further, a more acidic solution would have a lower pKa.

Example Question #3 : Strong And Weak Acids And Bases

Which of the following species will not be present in an aqueous solution of ?

Possible Answers:

All of these will be present in the solution

Correct answer:

Explanation:

The hydroxide ion (OH–) is a strong base and therefore would not be present in an acidic solution. Protons, the hydronium ion, and water will all be present in relatively large amounts within the solution. 

Example Question #4 : Strong And Weak Acids And Bases

Which of the following anions is the strongest base?

Possible Answers:

Correct answer:

Explanation:

Weaker acids dissociate less in water and therefore, reverse reaction is favored in 

. This indicates that the weaker the acid, the stronger its conjugate base.

, and  are all strong acids. Their conjugates are weak bases.

 has the weakest conjugate acid among the all the choices, so it is the strongest base.

Learning Tools by Varsity Tutors

Incompatible Browser

Please upgrade or download one of the following browsers to use Instant Tutoring: