Question 1

Which of the following best describes a Lewis acid?

Accepted Answer

A substance that accepts an electron pair

Question 2

Boron trifluoride ($$\mathrm{BF_3$}) is $$classified as a Lewis acid because:

Accepted Answer

It accepts an electron pair due to an incomplete octet

Question 3

Which of the following pairs represents a conjugate acid-base pair?

Accepted Answer

$$\mathrm{NH_4$^+}$$ \& $$\mathrm{NH_3$}$$

Question 4

A solution is prepared by mixing $$0.10 M $$acetic acid ($$\mathrm{CH_3COOH}$$, $$K_a = 1.8 	imes 10$$^{-5}$$) and 0.10$ M sodium acetate ($$\mathrm{CH_3COONa}$$). What is the pH of the buffer? (pK_a = 4.74$)

Accepted Answer

$$4.74$$

Question 5

Which of the following statements about buffer solutions is TRUE?

Accepted Answer

A buffer resists changes in pH when small amounts of acid or base are added

Question 6

Which of the following is an example of an amphoteric compound?

Accepted Answer

$$\mathrm{H_2O}$$

Question 7

Calculate the percent ionization of a $$0.10 M $$solution of formic acid ($$K_a = 1.8 	imes 10$$^{-4}$$).

Accepted Answer

$$4.2\%$$

Question 8

Which of the following best describes a nucleophile?

Accepted Answer

A species that donates an electron pair to form a bond

Question 9

Given the following equilibrium: $$\mathrm{HA} \rightleftharpoons \mathrm{H^+} + \mathrm{A^-}$$, which expression represents the acid dissociation constant $$K_a$$?

Accepted Answer

$$K_a = \dfrac{[\mathrm{H^+}][\mathrm{A^-}]}{[\mathrm{HA}]}$$

Question 10

A saturated solution of $$\mathrm{AgCl}$$ has a $$K_{sp} of$$ $$1.8 	imes 10$$^{-10}$$ at 25$$^\circ$$C. What is the molar solubility of $$\mathrm{AgCl}$$ in pure water?

Accepted Answer

$$1.3 	imes 10$$^{-5}$$ M

Question 11

Which of the following statements about $$K_{sp} is $$correct?

Accepted Answer

$$K_{sp} is $$the equilibrium constant for the dissolution of a sparingly soluble salt

Question 12

If the reaction quotient $$Q$$ for a salt is greater than its $$K_{sp}$$, what will happen when two solutions are mixed?

Accepted Answer

A precipitate will form

Question 13

Which of the following is a natural buffer system in the human body?

Accepted Answer

The bicarbonate/carbonic acid system

Question 14

A solution has $$[\mathrm{OH^-}] = 1.0 	imes 10$$^{-3}$$ M. What is the pOH of the solution?

Accepted Answer

$$3.00$$

Question 15

Which of the following best explains why $$\mathrm{$$BeH_2$$} is a $$Lewis acid?

Accepted Answer

It can accept an electron pair due to an incomplete octet

Question 16

Which of the following statements is TRUE regarding the relationship between $$pK_a$$ and acid strength?

Accepted Answer

A lower $$pK_a$$ value indicates a stronger acid

Question 17

A buffer is prepared by mixing $$0.20$$ mol of $$\mathrm{NH_3$}$$ and $$0.10$$ mol of $$\mathrm{NH_4Cl} in$$ $$1.0 L of $$solution. If $$K_b$$ for $$\mathrm{NH_3$} is$$ $$1.8 	imes 10$$^{-5}$$, what is the pH of the buffer? (pK_b = 4.74$)

Accepted Answer

$$9.04$$

Question 18

Which of the following best describes an electrophile?

Accepted Answer

A species that accepts an electron pair

Question 19

Which of the following salts will have the highest molar solubility in water, assuming all have the same $$K_{sp}$$ value?

Accepted Answer

$$\mathrm{AgCl}$$

Question 20

A solution is prepared by mixing $$50.0 mL of$$ $$0.10 M$$ $$\mathrm{NaF}$$ and $$50.0 mL of$$ $$0.10 M$$ $$\mathrm{HF}$$ ($$K_a = 6.8 	imes 10$$^{-4}$$). What is the pH of the resulting buffer? (pK_a = 3.17$)

Accepted Answer

$$3.17$$

Acids, Bases, Buffers, and Solubility: Study Guide for CHEM 107 Exam 4 (Chapters 16 & 17)

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