AP Chemistry : Reaction Types

Study concepts, example questions & explanations for AP Chemistry

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Example Questions

Example Question #121 : Reaction Types

Would H2SO4 or HNO3 produce a more acidic solution?

Possible Answers:

H2SO4 since it has a higher pKa

HNO3 since it has a higher pKa

H2SO4 since it has a lower pKa

HNO3 since it has a lower 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 #122 : Reaction Types

Which of the following species will not be present in an aqueous solution of \(\displaystyle H_2SO_4\)?

Possible Answers:

\(\displaystyle H^+\)

\(\displaystyle OH^-\)

All of these will be present in the solution

\(\displaystyle H_3O^+\)

\(\displaystyle H_2O\)

Correct answer:

\(\displaystyle OH^-\)

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 #22 : P H And Poh Of Strong Acids And Bases

Which of the following anions is the strongest base?

Possible Answers:

\(\displaystyle C_2H_3O_2^-\)

\(\displaystyle I^-\)

\(\displaystyle NO_3^-\)

\(\displaystyle ClO_4^-\)

Correct answer:

\(\displaystyle C_2H_3O_2^-\)

Explanation:

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

\(\displaystyle HX_{(aq)} + H_{2}O_{(l)} \rightleftharpoons H_{3}O_{(aq)} + X^{-}_{(aq)}\). This indicates that the weaker the acid, the stronger its conjugate base.

\(\displaystyle HI, HClO_4\), and \(\displaystyle HNO_3\) are all strong acids. Their conjugates are weak bases.

\(\displaystyle C_2H_3O_2^-\) has the weakest conjugate acid among the all the choices, so it is the strongest base.

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