Q: Which equation correctly relates pH and pOH in aqueous solution?

$$\text{pH} + \text{pOH} = 14$$

Q: A 0.00100 mol/L solution of potassium hydroxide, KOH(aq), is prepared. What is the concentration of hydrogen ions, [H$$^+$$], in this solution?

$$1.00 \times 10$$^{-11}$$ mol/L

Question 1

A chemist prepares a 0.025 mol/L solution of barium hydroxide, Ba(OH)$$_2(aq$$), a strong base. What is the concentration of hydroxide ions, [OH$$^-$$], in this solution?

Accepted Answer

$$0.050$$ mol/L

Question 2

Given a 0.13 mol/L solution of sodium hydroxide, NaOH(aq), what is the pH of the solution? (Assume complete dissociation and $$K_w = 1.0 	imes 10$$^{-14}$$)

Accepted Answer

$$13.11$$

Question 3

Which equation correctly relates pH and pOH in aqueous solution?

Accepted Answer

$$	ext{pH} + 	ext{pOH} = 14$$

Question 4

A 0.00100 mol/L solution of potassium hydroxide, KOH(aq), is prepared. What is the concentration of hydrogen ions, [H$$^+$$], in this solution?

Accepted Answer

$$1.00 	imes 10$$^{-11}$$ mol/L

Question 5

Which of the following statements about strong bases in aqueous solution is correct?

Accepted Answer

Strong bases dissociate completely, and their cations can be ignored when determining acid–base properties.

Question 6

A 2.00 L solution is prepared by dissolving 0.042 mol of Sr(OH)$$_2 in $$water. What is the pH of the solution?

Accepted Answer

$$12.92$$

Question 7

Industrial ammonia solutions are highly concentrated and corrosive. If the $$K_a$$ for NH$$_4^+ is$$ $$5.8 	imes 10$$^{-10}$$, what is the K_b$ for NH_3$?

Accepted Answer

$$1.7 	imes 10$$^{-5}$$

Question 8

A 15.0 mol/L solution of ammonia, NH$$_3(aq$$), is prepared. Using $$K_b = 1.7 	imes 10$$^{-5}$$, what is the approximate pH of the solution?

Accepted Answer

$$12.21$$

Question 9

Which of the following is the correct equilibrium constant expression for the ionization of a weak base, B(aq)?

Accepted Answer

$$K_b = \frac{[BH^+][OH^-]}{[B]}$$

Question 10

A base has a $$K_b of$$ $$3.82 	imes 10$$^{-10}$$ and a concentration of 0.20$ mol/L. What is the pH of the solution?

Accepted Answer

$$8.94$$

Question 11

If the $$K_a$$ for a conjugate acid is $$7.2 	imes 10$$^{-4}$$, what is the K_b$ for its conjugate base?

Accepted Answer

$$1.4 	imes 10$$^{-11}$$

Question 12

A 0.00040 mol/L solution of Ca(OH)$$_2 is $$prepared. What is the concentration of hydroxide ions, [OH$$^-$$], in the solution?

Accepted Answer

$$0.00080$$ mol/L

Question 13

A pharmaceutical company requires a solution of 0.25 mol/L methylamine (CH$$_3NH$_2) $$for its reactions. The chemist measures the pH and finds it to be 11.2. Is the solution too concentrated or too dilute?

Accepted Answer

Too dilute

Question 14

Which of the following best explains why the contribution of hydroxide ions from water autoionization can be ignored in strong base solutions?

Accepted Answer

The concentration of OH$$^-$$ from the base is much greater than from water autoionization.

Question 15

A 0.20 mol/L solution of N,N-diethylethanamine, (C$$_2H$_5$$)$$_3N(aq$$), has $$K_b = 4.0 	imes 10$$^{-4}$$. What is the hydroxide ion concentration, [OH$$^-$$], at equilibrium?

Accepted Answer

$$8.9 	imes 10$$^{-3}$$ mol/L

Question 16

Which equation shows the relationship between $$K_a$$, $$K_b$$, and $$K_w$$ for a conjugate acid-base pair?

Accepted Answer

$$K_a 	imes K_b = K_w$$

Question 17

A household ammonia solution has a pH of 11.80. What is its concentration? (Use $$K_b = 1.7 	imes 10$$^{-5}$$ for NH_3$)

Accepted Answer

$$0.18$$ mol/L

Question 18

A 0.01 mol/L solution of morphine, C$$_{17}H$_{19}NO$_3(aq$$), has $$K_b = 7.5 	imes 10$$^{-7}$$. What is the pH of the solution?

Accepted Answer

$$9.12$$

Question 19

Which real-world scenario best illustrates the importance of understanding the pH of basic solutions?

Accepted Answer

Determining the safety of industrial ammonia storage and handling.

Lesson 8.5: Calculations Involving Basic Solutions: Strong and Weak Bases

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