Q: A sample of gas occupies 2.50 L at 1.00 atm and 300 K. What will be its volume at 2.00 atm and 300 K, assuming the amount of gas remains constant?

$$V_2$$ = \frac{$$P_1$$ $$V_1$$}{$$P_2$$} = \frac{1.00 \times 2.50}{2.00} = 1.25\ \text{L}$$

Q: A 0.500 M NaCl solution is prepared by dissolving NaCl in water to make 250.0 mL of solution. How many grams of NaCl are required? (Molar mass of NaCl = 58.44 g/mol)

$$\text{mass} = M \times V \times \text{molar mass} = 0.500 \times 0.250 \times 58.44 = 7.305\ \text{g}$$

Q: A mixture of gases contains 2.0 mol N$$_2$$, 1.0 mol O$$_2$$, and 1.0 mol CO$$_2 in a 10.0 L $$container at 300 K. What is the total pressure of the mixture? ($$R = 0.0821\ \text{L} \cdot \text{atm} / \text{mol} \cdot \text{K})$$

$$P = \frac{nRT}{V} = \frac{4.0 \times 0.0821 \times 300}{10.0} = 9.85\ \text{atm}$$

Q: A solution is prepared by dissolving 5.00 g of glucose (C$$_6H$_{12}O$_6$$, molar mass = 180.16 g/mol) in 95.0 g of water. What is the molality of the solution?

$$\text{molality} = \frac{\text{moles solute}}{\text{kg solvent}} = \frac{5.00/180.16}{0.0950} = 0.292\ \text{m}$$

Q: A 10.0 g sample of KCl is dissolved in enough water to make 200.0 mL of solution. What is the molarity of the solution? (Molar mass of KCl = 74.55 g/mol)

$$M = \frac{\text{moles}}{\text{L}} = \frac{10.0/74.55}{0.200} = 0.670\ \text{M}$$

Question 1

Which of the following molecules violates the octet rule when drawing its Lewis structure?

Accepted Answer

BF$$_3$$

Question 2

Which of the following best describes the geometry of a molecule with four electron groups around the central atom according to VSEPR theory?

Accepted Answer

Tetrahedral

Question 3

A sample of gas occupies 2.50 L at 1.00 atm and 300 K. What will be its volume at 2.00 atm and 300 K, assuming the amount of gas remains constant?

Accepted Answer

$$V_2$$ = \frac{$$P_1$$ $$V_1$$}{$$P_2$$} = \frac{1.00 	imes 2.50}{2.00} = 1.25\ 	ext{L}$$

Question 4

Which of the following statements about resonance structures is correct?

Accepted Answer

Resonance structures are a way to show delocalized electrons within a molecule.

Question 5

Which of the following pairs of atoms will form the most polar covalent bond?

Accepted Answer

H and F

Question 6

A 0.500 M NaCl solution is prepared by dissolving NaCl in water to make 250.0 mL of solution. How many grams of NaCl are required? (Molar mass of NaCl = 58.44 g/mol)

Accepted Answer

$$	ext{mass} = M 	imes V 	imes 	ext{molar mass} = 0.500 	imes 0.250 	imes 58.44 = 7.305\ 	ext{g}$$

Question 7

Which of the following best explains why water (H$$_2O) is a $$polar molecule?

Accepted Answer

Water has polar bonds and a bent molecular geometry.

Question 8

A mixture of gases contains 2.0 mol N$$_2$$, 1.0 mol O$$_2$$, and 1.0 mol CO$$_2 in a 10.0 L $$container at 300 K. What is the total pressure of the mixture? ($$R = 0.0821\ 	ext{L} \cdot 	ext{atm} / 	ext{mol} \cdot 	ext{K})$$

Accepted Answer

$$P = \frac{nRT}{V} = \frac{4.0 	imes 0.0821 	imes 300}{10.0} = 9.85\ 	ext{atm}$$

Question 9

Which of the following is true about electrolytes?

Accepted Answer

Electrolytes conduct electricity because they dissociate into ions in solution.

Question 10

A solution is prepared by dissolving 5.00 g of glucose (C$$_6H$_{12}O$_6$$, molar mass = 180.16 g/mol) in 95.0 g of water. What is the molality of the solution?

Accepted Answer

$$	ext{molality} = \frac{	ext{moles solute}}{	ext{kg solvent}} = \frac{5.00/180.16}{0.0950} = 0.292\ 	ext{m}$$

Question 11

Which of the following correctly describes the relationship between pressure and volume for a fixed amount of gas at constant temperature (Boyle’s Law)?

Accepted Answer

$$P V = 	ext{constant}$$

Question 12

Which of the following is the correct Lewis structure for the ammonium ion (NH$$_4^+$$)?

Accepted Answer

N at the center with four single bonds to H atoms and a positive charge on the ion.

Question 13

A 10.0 g sample of KCl is dissolved in enough water to make 200.0 mL of solution. What is the molarity of the solution? (Molar mass of KCl = 74.55 g/mol)

Accepted Answer

$$M = \frac{	ext{moles}}{	ext{L}} = \frac{10.0/74.55}{0.200} = 0.670\ 	ext{M}$$

Question 14

Which of the following best describes the effect of increasing temperature on the solubility of a solid in water?

Accepted Answer

Solubility generally increases with increasing temperature.

Question 15

A gas is collected over water at 25$$^\circC. $$The total pressure is 755 mmHg, and the vapor pressure of water at this temperature is 23.8 mmHg. What is the pressure of the dry gas?

Accepted Answer

$$P_{	ext{gas}} = P_{	ext{total}} - P$$_{	ext{H}$$_2O} = 755 - 23.8 = 731.2\ 	ext{mmHg}$$

Question 16

Which of the following is the correct formula for calculating mass percent of a solute in a solution?

Accepted Answer

$$	ext{Mass percent} = \frac{	ext{mass of solute}}{	ext{mass of solution}} 	imes 100\%$$

Question 17

Which of the following statements about the kinetic molecular theory of gases is FALSE?

Accepted Answer

Gas particles experience significant attractive forces.

Question 18

A 500.0 mL sample of 2.00 M HCl is diluted to a final volume of 2.00 L. What is the final concentration?

Accepted Answer

$$M_1$$ $$V_1$$ = $$M_2$$ $$V_2$$ \Rightarrow $$M_2$$ = \frac{$$M_1$$ $$V_1$$}{$$V_2$$} = \frac{2.00 	imes 0.500}{2.00} = 0.500\ 	ext{M}$$

Question 19

Which of the following best describes the shape of a molecule with three electron groups and one lone pair on the central atom?

Accepted Answer

Bent

Study Notes: Chemical Bonding, Gases, and Solutions (Chapters 10, 11, 13)

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