Q: What is the $$[\mathrm{OH^-}] in a pH 12.479 $$aqueous solution, to the correct number of significant figures?

$$3.3189 \times 10$$^{-2}$$\ \mathrm{M}$$

Question 1

For the reaction $$2\ \mathrm{SO_2$(g)} + \mathrm{O_2$(g)} \rightleftharpoons 2\ \mathrm{SO_3$(g)}$$, what is the correct expression for the reaction quotient $$Q in $$terms of partial pressures?

Accepted Answer

$$Q = \dfrac{P_{\mathrm{SO_3$}}^2}{P_{\mathrm{SO_2$}}^2 P_{\mathrm{O_2$}}}$$

Question 2

A reaction vessel at 830 K contains 0.10 atm SO$$_2$$, 0.40 atm SO$$_3$$, and 0.50 atm O$$_2. $$For the reaction $$2\ \mathrm{SO_2$(g)} + \mathrm{O_2$(g)} \rightleftharpoons 2\ \mathrm{SO_3$(g)}$$, $$K_p = 7.7 at 830 K. $$What is the value of the reaction quotient $$Q$$ for this mixture, and in which direction will the reaction proceed to reach equilibrium?

Accepted Answer

$$Q = 3.2$$, right to left

Question 3

Given the acid-base reaction below, identify the two conjugate acid-base pairs.

$$\mathrm{H_2O} + \mathrm{CH_3COOH} \rightleftharpoons \mathrm{CH_3COO^-} + \mathrm{H_3O^+}$$

Accepted Answer

(1/4) and (2/3)

Question 4

The equilibrium constant for the above reaction is $$2 	imes 10$$^{-5}$$ at 25$$^\circ$$C. Which compound is the strongest acid in the reaction?

Accepted Answer

$$\mathrm{H_3O^+}$$

Question 5

A solution has $$[\mathrm{H_3O^+}] = 1.0 	imes 10$$^{-10}$$\ \mathrm{M} at 25$^\circC. $$What is the pH and pOH of the solution?

Accepted Answer

pH = 7.0, pOH = 7.0

Question 6

What is the $$[\mathrm{OH^-}] in a pH 12.479 $$aqueous solution, to the correct number of significant figures?

Accepted Answer

$$3.3189 	imes 10$$^{-2}$$\ \mathrm{M}$$

Question 7

If 5.0 mL of a 0.050 M aqueous solution of HI is diluted to 125.0 mL, what is the pH of the resulting solution?

Accepted Answer

2.70

Question 8

How many grams of HI are needed to make 500.0 mL of a pH 1.07 aqueous solution?

Accepted Answer

0.51 g HI

Question 9

What is the acid dissociation reaction for glycolyic acid, $$\mathrm{HC(O)CO_2H}$$?

Accepted Answer

$$\mathrm{HC(O)CO_2H} + \mathrm{H_2O} \rightarrow \mathrm{HC(O)CO_2$^-} + \mathrm{H_3O^+}$$

Question 10

What is the pH of a 0.25 M solution of glycolic acid, $$\mathrm{HC(O)CO_2H}$$, $$K_a = 3.5 	imes 10$$^{-4}$$?

Accepted Answer

2.03

Question 11

Which of the following structures CANNOT possibly be a reasonable Lewis structure for a molecule with the formula $$\mathrm{C_2H_6O}$$?

Accepted Answer

A structure with a carbon atom having five bonds

Question 12

How are two resonance structures of the same compound related to each other?

Accepted Answer

They are completely equivalent resonance structures of the same compound

Question 13

Which of the following is a good 3D representation of the adjacent organic compound (lactone)?

Accepted Answer

A structure with a five-membered ring and an ester group

Question 14

Which of the following is the correct molecular formula for wine lactone, a compound found in white wine?

Accepted Answer

$$\mathrm{C_6H_{10}O_2$}$$

Question 15

Which of the following is a reasonable 3D representation of the correct Lewis structure for $$\mathrm{$$BrCl_3$$}$$?

Accepted Answer

A structure with Br in the center, three Cl atoms bonded, and two lone pairs on Br

Question 16

Which one of the structures for $$\mathrm{$$BrCl_3$$}$$ has Br with a +3 formal charge?

Accepted Answer

A structure where Br has no lone pairs and is bonded to three Cl atoms

Question 17

What is the balanced net ionic equation for the reaction: $$\mathrm{Cr($$ClO_4$$)_3(aq) + KOH(aq) \rightarrow K[Cr(OH)_4](aq) + $$KClO_4$$(aq)}$$?

Accepted Answer

$$\mathrm{Cr$$^{3+}$$(aq) + 4\ OH^-(aq) \rightarrow [Cr(OH)_4]^-(aq)}$$

Question 18

If 25.0 mL of a 0.036 M $$\mathrm{Cr($$ClO_4$$)_3}$$ solution is mixed with 75.0 mL of a 0.045 M KOH solution, how many moles of $$\mathrm{K[Cr(OH)_4]}$$ will be made, assuming the reaction goes to completion?

Accepted Answer

$$2.7 	imes 10$$^{-3}$$ mol

Question 19

Based on the following $$K_a$$ values, which of the following will be the weakest base? $$K_a$$ values: (A) $$1.4 	imes 10$$^{-3}$$, (B) 1.4$$ 	imes $$10^{-4}$$, (C) $$1.3 	imes 10$$^{-5}$$.

Accepted Answer

A

Question 20

A certain weak base, B, has $$K_b = 1.6 	imes 10$$^{-5}$$. A solution of B is prepared by dissolving 5.00 g in 75.0 mL of water. The pH of the solution is 10.773. What is the molecular weight of B?

Accepted Answer

78.3 g/mol

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