Q: A solution is prepared by dissolving 10.0 g of NaCl (molar mass = 58.44 g/mol) in enough water to make 500.0 mL of solution. What is the molarity of the solution?

$$ \displaystyle \frac{10.0}{58.44} = 0.171 \text{ mol};\ \frac{0.171}{0.500} = 0.342\ \mathrm{M} $$

Q: What is the mass percent of ethanol in a solution made by dissolving 20.0 g of ethanol in 80.0 g of water?

$$ \displaystyle \frac{20.0}{20.0 + 80.0} \times 100\% = 20.0\% $$

Q: How many moles of solute are present in 250 mL of a 0.40 M NaOH solution?

$$ 0.250\ \mathrm{L} \times 0.40\ \mathrm{mol/L} = 0.10\ \mathrm{mol} $$

Q: A 2.0 M HCl solution is diluted to a final volume of 500 mL. If the initial volume was 100 mL, what is the final concentration?

$$ M_1V_1 = M_2V_2;\ 2.0\ \mathrm{M} \times 0.100\ \mathrm{L} = M_2$ \times 0.500\ \mathrm{L};\ M_2$ = 0.40\ \mathrm{M} $$

Q: What is the pH of a solution with $$ [\mathrm{H^+}] = 1.0 \times 10$$^{-4}$$\ \mathrm{M} $$?

$$ \mathrm{pH} = -\log(1.0 \times 10$$^{-4}$$) = 4.00 $$

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?

$$ M_1V_1 = M_2V_2;\ 0.100\ \mathrm{M} \times 25.0\ \mathrm{mL} = M_2$ \times 50.0\ \mathrm{mL};\ M_2$ = 0.050\ \mathrm{M} $$

Question 1

Which of the following molecules violates the octet rule?

Accepted Answer

$$ \mathrm{BF_3$} $$

Question 2

What is the correct Lewis structure for carbon dioxide ($$ \mathrm{CO_2$} $$)?

Accepted Answer

O=C=O, with each O atom having two lone pairs

Question 3

Which element below has the highest electronegativity?

Accepted Answer

$$ \mathrm{F} $$

Question 4

Given the Lewis structure of ammonia ($$ \mathrm{NH_3$} $$), what is its molecular geometry and is it polar?

Accepted Answer

Trigonal pyramidal; polar

Question 5

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

Accepted Answer

$$ \mathrm{CH_3OH}  ($$methanol)

Question 6

Which type of intermolecular force is present in all molecular substances, regardless of polarity?

Accepted Answer

Dispersion (London) forces

Question 7

Identify the functional group present in the following molecule: $$ \mathrm{CH_3COOH} $$

Accepted Answer

Carboxylic acid

Question 8

Which of the following is an alkene?

Accepted Answer

$$ \mathrm{C_2H_4}  ($$ethene)

Question 9

A solution is prepared by dissolving 10.0 g of NaCl (molar mass = 58.44 g/mol) in enough water to make 500.0 mL of solution. What is the molarity of the solution?

Accepted Answer

$$ \displaystyle \frac{10.0}{58.44} = 0.171 	ext{ mol};\ \frac{0.171}{0.500} = 0.342\ \mathrm{M} $$

Question 10

What is the mass percent of ethanol in a solution made by dissolving 20.0 g of ethanol in 80.0 g of water?

Accepted Answer

$$ \displaystyle \frac{20.0}{20.0 + 80.0} 	imes 100\% = 20.0\% $$

Question 11

How many moles of solute are present in 250 mL of a 0.40 M NaOH solution?

Accepted Answer

$$ 0.250\ \mathrm{L} 	imes 0.40\ \mathrm{mol/L} = 0.10\ \mathrm{mol} $$

Question 12

A 2.0 M HCl solution is diluted to a final volume of 500 mL. If the initial volume was 100 mL, what is the final concentration?

Accepted Answer

$$ M_1V_1 = M_2V_2;\ 2.0\ \mathrm{M} 	imes 0.100\ \mathrm{L} = M_2$ 	imes 0.500\ \mathrm{L};\ M_2$ = 0.40\ \mathrm{M} $$

Question 13

Which of the following best describes a Bronsted-Lowry acid?

Accepted Answer

A substance that donates a proton ($$ \mathrm{H^+} )$$

Question 14

What is the pH of a solution with $$ [\mathrm{H^+}] = 1.0 	imes 10$$^{-4}$$\ \mathrm{M} $$?

Accepted Answer

$$ \mathrm{pH} = -\log(1.0 	imes 10$$^{-4}$$) = 4.00 $$

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?

Accepted Answer

$$ M_1V_1 = M_2V_2;\ 0.100\ \mathrm{M} 	imes 25.0\ \mathrm{mL} = M_2$ 	imes 50.0\ \mathrm{mL};\ M_2$ = 0.050\ \mathrm{M} $$

Question 16

Which of the following molecules is non-polar despite having polar bonds?

Accepted Answer

$$ \mathrm{CO_2$} $$

Question 17

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

Accepted Answer

$$ \mathrm{HCl} $$ and $$ \mathrm{CH_3Cl} $$

Question 18

Which of the following is the correct IUPAC name for $$ \mathrm{CH_3CH_2CH_2CH_2CH_3} $$?

Accepted Answer

Pentane

Question 19

Which functional group is present in acetone ($$ \mathrm{CH_3COCH_3} $$)?

Accepted Answer

Ketone

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

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