Q: A solution has a pH of 3. What is the $$[OH^-]$$ concentration in this solution at 25°C?

$$1 \times 10$$^{-11}$$\ \text{mol/L}$$

Question 1

Which of the following best describes the mixture shown in the beaker with oil, water, and sand (see image)?

Accepted Answer

A heterogeneous mixture

Question 2

When salt is added to water and dissolves completely (see image), what type of mixture is formed?

Accepted Answer

A homogeneous solution

Question 3

A student prepares a solution by dissolving 10.0 g of NaCl (molar mass = 58.5 g/mol) in enough water to make 500 mL of solution. What is the molarity of the solution?

Accepted Answer

$$0.34\ 	ext{mol/L}$$

Question 4

Which of the following equations correctly relates the number of moles ($$n$$), concentration ($$C$$), and volume ($$V) of a $$solution?

Accepted Answer

$$n = C 	imes V$$

Question 5

A pharmacist needs to prepare 250 mL of a 0.2 M KCl solution from a 1.0 M stock solution. What volume of the stock solution should be used?

Accepted Answer

$$50\ 	ext{mL}$$

Question 6

Which of the following is a strong electrolyte?

Accepted Answer

Sodium chloride ($$NaCl)$$

Question 7

Which of the following best explains why pure water does not conduct electricity?

Accepted Answer

Water does not contain free ions

Question 8

Which of the following is the correct balanced chemical equation for the combustion of propane ($$C_3H_8$$)?

Accepted Answer

$$C_3H_8 + 5O_2 \rightarrow 3CO_2 + 4H_2O$$

Question 9

Which of the following is a net ionic equation for the reaction between $$Ca(OH)_2$$ and $$Na_2CO_3 in $$aqueous solution?

Accepted Answer

$$Ca^{2+}(aq$$) + $$CO_3$$^{2-}(aq) \rightarrow $$CaCO_3(s$$)$$

Question 10

Which of the following ions is a spectator ion in the reaction between $$BaI_2$$ and $$Na_2SO_4 to $$form $$BaSO_4$$?

Accepted Answer

$$Na^+$$ and I^-$

Question 11

According to the Brønsted-Lowry theory, which of the following acts as a base in the reaction $$NH_3(aq) + H_2O(l$$) \rightleftharpoons $$NH_4^+(aq) + OH^-(aq$$)$$?

Accepted Answer

$$NH_3$$

Question 12

What is the pH of a solution with $$[H_3O^+] = 2.0 	imes 10$$^{-5}$$\ 	ext{mol/L}$$?

Accepted Answer

$$4.7$$

Question 13

Which of the following statements about strong acids and weak acids is correct?

Accepted Answer

Strong acids have higher $$K_a$$ values than weak acids

Question 14

A 0.1 M solution of acetic acid ($$CH_3COOH) $$has a $$K_a = 1.8 	imes 10$$^{-5}$$. What is the pKa of acetic acid?

Accepted Answer

$$4.7$$

Question 15

Which of the following drugs is the strongest acid based on the given pKa values: Amphetamine (pKa = 9.8), Ampicillin (pKa = 2.7), Codeine (pKa = 7.9), Warfarin (pKa = 5.1)?

Accepted Answer

Ampicillin

Question 16

What is the relationship between $$K_a$$ and $$K_b$$ for a conjugate acid-base pair in water at 25°C?

Accepted Answer

$$K_a 	imes K_b = K_w$$

Question 17

A solution has a pH of 3. What is the $$[OH^-]$$ concentration in this solution at 25°C?

Accepted Answer

$$1 	imes 10$$^{-11}$$\ 	ext{mol/L}$$

Question 18

Which of the following salts will produce a basic solution when dissolved in water?

Accepted Answer

CH3COONa

Question 19

Calculate the percentage ionisation of a weak acid with pKa = 4.7 in a solution with pH = 2.7.

Accepted Answer

$$99\%$$

General Chemistry Study Notes: Solutions and Acid-Base Equilibria

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