Q: A solution is made by dissolving 10 g of NaCl in 90 g of water. What is the mass percent of NaCl in the solution?

$$\frac{10}{10+90} \times 100 = 10\%$$

Q: What is the molarity of a solution prepared by dissolving 58.5 g of NaCl (molar mass = 58.5 g/mol) in enough water to make 1.00 L of solution?

$$\frac{58.5\ \text{g}}{58.5\ \text{g/mol}} = 1\ \text{mol}$$; $$\frac{1\ \text{mol}}{1\ \text{L}} = 1\ \text{M}$$

Q: How many moles of solute are present in 250 mL of a 0.20 M NaOH solution?

$$0.20\ \text{mol/L} \times 0.250\ \text{L} = 0.050\ \text{mol}$$

Q: A 1.0 M solution of HCl is diluted to make 0.25 M solution. If you start with 100 mL of the 1.0 M solution, what final volume will you have after dilution?

$$M_1V_1 = M_2V_2$$; $$1.0 \times 100 = 0.25 \times V_2$; V_2$ = 400\ \text{mL}$$

Q: Calculate the pH of a solution with a hydrogen ion concentration of $$1 \times 10$$^{-4}$$ M.

$$\text{pH} = -\log(1 \times 10$$^{-4}$$) = 4$$

Q: During a titration, 25.0 mL of 0.100 M NaOH is required to neutralize 50.0 mL of HCl. What is the concentration of the HCl solution?

$$M_1V_1 = M_2V_2$$; $$0.100 \times 25.0 = M_{HCl} \times 50.0$$; $$M_{HCl} = 0.050\ \text{M}$$

Q: A patient receives a saline solution containing 0.90 g NaCl in 100 mL of water. What is the molarity of NaCl in the solution? (NaCl molar mass = 58.5 g/mol)

$$\frac{0.90\ \text{g}}{58.5\ \text{g/mol}} = 0.0154\ \text{mol}$$; $$\frac{0.0154\ \text{mol}}{0.100\ \text{L}} = 0.154\ \text{M}$$

Question 1

Which of the following molecules violates the octet rule?

Accepted Answer

BF$$_3$$

Question 2

What is the correct Lewis structure for the nitrate ion (NO$$_3^-$$)? How many bonding pairs and lone pairs are present on the central atom?

Accepted Answer

3 bonding pairs, 0 lone pairs

Question 3

Which element has the highest electronegativity according to periodic trends?

Accepted Answer

Fluorine

Question 4

Given the Lewis structure of water (H$$_2O$$), what is its molecular geometry and is it polar or non-polar?

Accepted Answer

Bent, polar

Question 5

Which intermolecular force is responsible for the high boiling point of water?

Accepted Answer

Hydrogen bonding

Question 6

Which of the following molecules can form hydrogen bonds with itself?

Accepted Answer

CH$$_3NH$_2$$

Question 7

Identify the functional group present in the molecule CH$$_3$$COOH.

Accepted Answer

Carboxylic acid

Question 8

Which hydrocarbon is an alkene?

Accepted Answer

C$$_2H$_4$$

Question 9

A solution is made by dissolving 10 g of NaCl in 90 g of water. What is the mass percent of NaCl in the solution?

Accepted Answer

$$\frac{10}{10+90} 	imes 100 = 10\%$$

Question 10

What is the molarity of a solution prepared by dissolving 58.5 g of NaCl (molar mass = 58.5 g/mol) in enough water to make 1.00 L of solution?

Accepted Answer

$$\frac{58.5\ 	ext{g}}{58.5\ 	ext{g/mol}} = 1\ 	ext{mol}$$; $$\frac{1\ 	ext{mol}}{1\ 	ext{L}} = 1\ 	ext{M}$$

Question 11

How many moles of solute are present in 250 mL of a 0.20 M NaOH solution?

Accepted Answer

$$0.20\ 	ext{mol/L} 	imes 0.250\ 	ext{L} = 0.050\ 	ext{mol}$$

Question 12

A 1.0 M solution of HCl is diluted to make 0.25 M solution. If you start with 100 mL of the 1.0 M solution, what final volume will you have after dilution?

Accepted Answer

$$M_1V_1 = M_2V_2$$; $$1.0 	imes 100 = 0.25 	imes V_2$; V_2$ = 400\ 	ext{mL}$$

Question 13

Which of the following statements best describes a Bronsted-Lowry base?

Accepted Answer

A substance that accepts a proton (H$$^+)$$

Question 14

Calculate the pH of a solution with a hydrogen ion concentration of $$1 	imes 10$$^{-4}$$ M.

Accepted Answer

$$	ext{pH} = -\log(1 	imes 10$$^{-4}$$) = 4$$

Question 15

During a titration, 25.0 mL of 0.100 M NaOH is required to neutralize 50.0 mL of HCl. What is the concentration of the HCl solution?

Accepted Answer

$$M_1V_1 = M_2V_2$$; $$0.100 	imes 25.0 = M_{HCl} 	imes 50.0$$; $$M_{HCl} = 0.050\ 	ext{M}$$

Question 16

Which molecule below is non-polar despite having polar bonds?

Accepted Answer

CO$$_2$$

Question 17

Which of the following pairs of molecules can form dipole-dipole interactions with each other?

Accepted Answer

H$$_2O $$and H$$_2S$$

Question 18

Which functional group is present in the molecule CH$$_3CH$_2$$OCH$$_2CH$_3$$?

Accepted Answer

Ether

Question 19

A patient receives a saline solution containing 0.90 g NaCl in 100 mL of water. What is the molarity of NaCl in the solution? (NaCl molar mass = 58.5 g/mol)

Accepted Answer

$$\frac{0.90\ 	ext{g}}{58.5\ 	ext{g/mol}} = 0.0154\ 	ext{mol}$$; $$\frac{0.0154\ 	ext{mol}}{0.100\ 	ext{L}} = 0.154\ 	ext{M}$$

CHEM 1120 Exam III Study Guide: Chemical Bonding, Intermolecular Forces, Solutions, Acids and Bases, and Organic Chemistry

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