Q: A solution is prepared by dissolving 0.10 mol of $$\mathrm{NaF} in 1.0 L of $$water. If the $$K_{sp} of$$ $$\mathrm{$$CaF_2$$} is$$ $$3.9 \times 10$$^{-11}$$, what is the maximum concentration of $$\mathrm{$$Ca^{2+}$$}$$ that can be present before precipitation occurs?

$$3.9 \times 10$$^{-9}$$\ \mathrm{M}$$

Q: A saturated solution of $$\mathrm{AgCl} is $$prepared. If $$K_{sp} = 1.8 \times 10$$^{-10}$$, what is the molar solubility of $$\mathrm{AgCl}$$ in pure water?

$$1.3 \times 10$$^{-5}$$\ \mathrm{M}$$

Question 1

A 0.10 M solution of acetic acid ($$\mathrm{CH_3COOH}$$, $$K_a = 1.8 	imes 10$$^{-5}$$) is prepared. What is the pH of this solution?

Accepted Answer

$$\mathrm{pH} = 2.87$$

Question 2

Which of the following best describes the common ion effect?

Accepted Answer

The suppression of the ionization of a weak acid or base by the addition of a strong electrolyte containing a common ion.

Question 3

A buffer is prepared by mixing 0.20 mol of ammonia ($$\mathrm{NH_3$}) $$and 0.20 mol of ammonium chloride ($$\mathrm{NH_4Cl}) in $$enough water to make 1.0 L of solution. ($$K_b$$ for $$\mathrm{NH_3$} = 1.8 	imes 10$$^{-5}$$). What is the pH of the buffer? (pK_b = 4.74$)

Accepted Answer

$$\mathrm{pH} = 9.25$$

Question 4

Which equation is used to calculate the pH of a buffer solution?

Accepted Answer

$$\mathrm{pH} = pK_a + \log \left( \frac{[\mathrm{A}^-]}{[\mathrm{HA}]} \right)$$

Question 5

During a titration of a weak acid with a strong base, which of the following best describes the pH at the equivalence point?

Accepted Answer

The pH is greater than 7 because the conjugate base of the weak acid hydrolyzes to produce $$\mathrm{OH}^-.$$

Question 6

Which of the following statements about polyprotic acids is correct?

Accepted Answer

Each successive ionization has a smaller $$K_a$$ value than the previous one.

Question 7

A solution is prepared by dissolving 0.10 mol of $$\mathrm{NaF} in 1.0 L of $$water. If the $$K_{sp} of$$ $$\mathrm{$$CaF_2$$} is$$ $$3.9 	imes 10$$^{-11}$$, what is the maximum concentration of $$\mathrm{$$Ca^{2+}$$}$$ that can be present before precipitation occurs?

Accepted Answer

$$3.9 	imes 10$$^{-9}$$\ \mathrm{M}$$

Question 8

Which of the following best explains why adding $$\mathrm{HCl} to a $$solution of sodium acetate ($$\mathrm{NaCH_3COO}) $$decreases the pH?

Accepted Answer

The added $$\mathrm{H^+}$$ reacts with $$\mathrm{CH_3COO^-} to $$form $$\mathrm{CH_3COOH}$$, reducing the concentration of base and increasing the concentration of acid.

Question 9

Which of the following is true regarding the buffer capacity of a solution?

Accepted Answer

Buffer capacity is greatest when the concentrations of acid and conjugate base are high and approximately equal.

Question 10

A saturated solution of $$\mathrm{AgCl} is $$prepared. If $$K_{sp} = 1.8 	imes 10$$^{-10}$$, what is the molar solubility of $$\mathrm{AgCl}$$ in pure water?

Accepted Answer

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

Question 11

Which of the following best describes what happens when $$Q \u003e K_{sp}$$ for a slightly soluble salt?

Accepted Answer

A precipitate will form until $$Q = K_{sp}.$$

Question 12

During a titration of 25.0 mL of 0.100 M $$\mathrm{HCl}$$ with 0.100 M $$\mathrm{NaOH}$$, what is the pH after adding 30.0 mL of $$\mathrm{NaOH}$$?

Accepted Answer

$$\mathrm{pH} = 12.70$$

Question 13

Which of the following is the correct expression for the solubility product constant ($$K_{sp}) $$for $$\mathrm{Ca_3$(PO_4$)_2}$$?

Accepted Answer

$$K_{sp} = [\mathrm{Ca$$^{2+}$$}]^3[\mathrm{PO_4$^{3-}}]^2$$

Question 14

Which of the following best explains why the pH of a 0.10 M solution of $$\mathrm{NaCl} is 7.00$$?

Accepted Answer

Neither $$\mathrm{Na^+}$$ nor $$\mathrm{Cl^-}$$ hydrolyze in water, so the solution remains neutral.

Question 15

Which of the following is the correct 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 16

A buffer solution is made by mixing 0.50 mol of $$\mathrm{H_2CO_3}$$ and 0.25 mol of $$\mathrm{$$NaHCO_3$$} in 1.0 L of $$water. If $$pK_a = 6.35$$, what is the pH of the buffer?

Accepted Answer

$$\mathrm{pH} = 6.05$$

Question 17

Which of the following best describes the purpose of a buffer in a biological system?

Accepted Answer

To maintain a relatively constant pH despite the addition of acids or bases.

Question 18

Which of the following is true about the effect of pH on the solubility of a salt containing a basic anion (e.g., $$\mathrm{Mg(OH)_2}$$)?

Accepted Answer

Lowering the pH increases the solubility because $$\mathrm{H^+}$$ reacts with the basic anion.

Question 19

Which of the following best describes the region of a titration curve where the buffer is most effective?

Accepted Answer

The region where $$\mathrm{pH} \approx pK_a.$$

Acid-Base Chemistry, Buffers, Titrations, and Solubility Equilibria: Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard