Question 1

Which of the following acids has the strongest conjugate base? Use the $$K_a$$ values below:

$$\begin{array}{l|c}
	ext{Acid} & K_a \
\hline
	ext{HNO}_3 & 4.5 	imes 10^0$ \
	ext{HClO}_4 & 1.0 	imes 10^1$ \
	ext{HCN} & 4.9 	imes 10$$^{-10}$$ \
	ext{HCOOH} & 1.8 	imes 10$$^{-4}$$ \
\end{array}$$

Accepted Answer

HCN

Question 2

A solution of 0.01 M CH$$_3$$COOH (acetic acid) has a $$K_a = 1.8 	imes 10$$^{-5}$$. What is the concentration of H_3$O$$^+$$ ions at equilibrium?

Accepted Answer

$$4.2 	imes 10$$^{-4}$$ M

Question 3

Which of the following statements is true about strong acids?

Accepted Answer

They completely dissociate in water.

Question 4

Calculate the pH of a 0.025 M HNO$$_3$$ solution. Assume complete dissociation.

Accepted Answer

pH = $$-\log(0.025) = 1.60$$

Question 5

A buffer is made by mixing 0.10 mol of NH$$_3$$ and 0.10 mol of NH$$_4Cl in 1.0 L of $$solution. If $$K_b$$ for NH$$_3 is$$ $$1.8 	imes 10$$^{-5}$$, what is the pH of the buffer? (K_w = 1.0$$ 	imes $$10^{-14})

$$

Accepted Answer

pH = $$9.25$$

Question 6

Which of the following combinations would be best to prepare a buffer with a pH of 9.5?

Accepted Answer

NH$$_3$$ and NH$$_4Cl$$

Question 7

What is the solubility (in mol/L) of PbI$$_2 in $$water if $$K_{sp} = 8.5 	imes 10$$^{-9}$$?

Accepted Answer

$$1.3 	imes 10$$^{-3}$$

Question 8

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

Accepted Answer

NaNO$$_2$$

Question 9

A 0.10 M solution of a weak acid HA has a $$K_a = 1.0 	imes 10$$^{-5}$$. What is the pH of the solution?

Accepted Answer

pH = $$3.00$$

Question 10

Which of the following is the best indicator for a titration of a weak acid with a strong base?

Accepted Answer

Phenolphthalein

Question 11

Which of the following is true about the relationship between acid strength and conjugate base strength?

Accepted Answer

A strong acid has a weak conjugate base.

Question 12

Calculate the pH at the equivalence point for the titration of 0.100 M CH$$_3$$COOH with 0.100 M NaOH. ($$K_a$$ for CH$$_3$$COOH = $$1.8 	imes 10$$^{-5}$$)

Accepted Answer

pH = $$8.72$$

Question 13

Which of the following is the correct expression for the solubility product constant ($$K_{sp}) $$for Ca$$_3(PO$_4$$)$$_2$$?

Accepted Answer

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

Question 14

A solution is prepared by mixing 0.10 M NH$$_3$$ and 0.10 M NH$$_4Cl. $$What is the ratio $$\dfrac{[NH_3$]}{[NH_4$^+]}$$ when the pH equals the p$$K_a of NH$_4^+$$?

Accepted Answer

1

Question 15

Which of the following will increase the solubility of AgCl in water?

Accepted Answer

Adding NH$$_3$$

Question 16

A 0.10 M solution of a weak base B has a $$K_b = 1.0 	imes 10$$^{-5}$$. What is the pOH of the solution?

Accepted Answer

pOH = $$5.00$$

Question 17

Which of the following is the best choice for a buffer with a pH near 5?

Accepted Answer

CH$$_3$$COOH and CH$$_3$$COONa

Question 18

Which of the following is the correct formula for calculating the pH of a weak acid solution?

Accepted Answer

$$pH = -\log([H_3O^+])$$

Question 19

A 0.10 M solution of HCN ($$K_a = 4.9 	imes 10$$^{-10}$$) is prepared. What is the pH of the solution?

Accepted Answer

pH = $$5.00$$

Acids, Bases, and Equilibrium: General Chemistry Study Notes

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