Question 1

Which of the following salts will produce an acidic solution when dissolved in water?

Accepted Answer

NH4NO3

Question 2

Why do small, highly charged cations such as $$Fe^{3+}$$ act as Lewis acids in aqueous solution?

Accepted Answer

They accept electron pairs from water molecules, increasing the acidity of the solution.

Question 3

Which of the following ions is most likely to behave as a base in water?

Accepted Answer

$$CO_3$$^{2-}$$

Question 4

Given the following equilibrium: $$HA + H_2O \rightarrow H_3O^+ + A^-$$, what makes an acid strong according to the study materials?

Accepted Answer

A strong acid has a weak conjugate base that is very stable.

Question 5

Which trend is observed for the acidity of metal cations in water?

Accepted Answer

Acidity increases with increasing charge and decreasing size.

Question 6

What is the $$K_a$$ expression for the dissociation of carbonic acid ($$H_2CO_3) in $$water?

Accepted Answer

$$K_a = \frac{[$$HCO_3$$^-][H^+]}{[H_2CO_3]}$$

Question 7

Which of the following statements best explains why $$NH_4F is $$acidic in water?

Accepted Answer

Both $$NH_4$$^+$$ and F$$^-$$ are weak acids, but NH_4$^+ is a $$stronger acid than $$F^- is a $$base.

Question 8

Which of the following is a correct Lewis acid-base pair?

Accepted Answer

$$Fe^{3+} ($$acid) and $$H_2O ($$base)

Question 9

Which of the following will result in a neutral solution when dissolved in water?

Accepted Answer

KBr

Question 10

Why does acetic acid ($$CH_3COOH) $$have a higher $$K_a$$ than ethanol ($$C_2H_5OH$$)?

Accepted Answer

Acetic acid has resonance stabilization in its conjugate base.

Question 11

Which of the following is the correct $$K_b$$ expression for the reaction $$CO_3$$^{2-} + H_2O \rightarrow $$HCO_3^- + OH$$^-$$?

Accepted Answer

$$K_b = \frac{[$$HCO_3$$^-][OH^-]}{[CO_3$^{2-}]}$$

Question 12

Which of the following factors increases the acidity of oxoacids?

Accepted Answer

Increasing the number of oxygen atoms bonded to the central atom.

Question 13

What is the effect of resonance in the conjugate base on acid strength?

Accepted Answer

More resonance in the conjugate base increases acid strength.

Question 14

Which of the following is the correct $$K_a$$ value for formic acid ($$HCOOH) as $$given in the study materials?

Accepted Answer

$$K_a = 1.8 	imes 10$$^{-4}$$

Question 15

Which statement best explains why $$AlCl_3 is $$acidic in water?

Accepted Answer

$$Al^{3+} is a $$small, highly charged cation that acts as a Lewis acid.

Question 16

Which of the following is true about the relationship between $$K_a$$ and $$K_b$$ for a conjugate acid-base pair?

Accepted Answer

$$K_a 	imes K_b = K_w$$

Question 17

Which of the following is a correct statement about the acidity of $$HClO_3$$ compared to $$HClO$$?

Accepted Answer

$$HClO_3 is $$more acidic because it has more oxygen atoms.

Question 18

Which of the following best describes the effect of bond strength on acid strength for binary acids?

Accepted Answer

Weaker H-A bonds result in stronger acids.

Question 19

Which of the following is a correct $$K_a$$ expression for acetic acid ($$CH_3COOH$$)?

Accepted Answer

$$K_a = \frac{[CH_3COO^-][H^+]}{[CH_3COOH]}$$

Question 20

Which of the following is a correct statement about the effect of electronegativity on oxoacid strength?

Accepted Answer

Higher electronegativity of the central atom increases acid strength.

Cations, Anions, and Acid-Base Properties in Aqueous Solutions

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