Q: Which of the following statements about the mole is correct?

One mole contains $6.022 \times 10^{23}$ entities, known as Avogadro's number.

Q: Which of the following is the correct formula for calculating molarity ($M$)?

$M = \frac{\text{moles of solute}}{\text{liters of solution}}$

Question 1

Which of the following is the correct balanced chemical equation for the combustion of methane ($\mathrm{CH_4}$) in oxygen?

Accepted Answer

$\mathrm{CH_4} + 2\mathrm{O_2} \rightarrow \mathrm{CO_2} + 2\mathrm{H_2O}$

Question 2

A sample contains $18.0\ \mathrm{g}$ of water ($\mathrm{H_2O}$). How many moles of water are present? (Molar mass of $\mathrm{H_2O}$ is $18.0\ \mathrm{g/mol}$)

Accepted Answer

$1.0\ \mathrm{mol}$

Question 3

A compound contains $40.0\%$ carbon, $6.7\%$ hydrogen, and $53.3\%$ oxygen by mass. What is its empirical formula?

Accepted Answer

$\mathrm{CH_2O}$

Question 4

Which of the following statements about the mole is correct?

Accepted Answer

One mole contains $6.022 	imes 10^{23}$ entities, known as Avogadro's number.

Question 5

A reaction yields $15.0\ \mathrm{g}$ of product, but the theoretical yield is $20.0\ \mathrm{g}$. What is the percent yield?

Accepted Answer

$75\%$

Question 6

If $0.50\ \mathrm{mol}$ of $\mathrm{NaCl}$ is dissolved in enough water to make $250\ \mathrm{mL}$ of solution, what is the molarity?

Accepted Answer

$2.0\ \mathrm{M}$

Question 7

Which of the following is a correct net ionic equation for the reaction between $\mathrm{AgNO_3}$ and $\mathrm{NaCl}$ in aqueous solution?

Accepted Answer

$\mathrm{Ag^+} (aq) + \mathrm{Cl^-} (aq) \rightarrow \mathrm{AgCl} (s)$

Question 8

A $100\ \mathrm{mL}$ solution of $0.50\ \mathrm{M}$ $\mathrm{HCl}$ is diluted to $400\ \mathrm{mL}$. What is the new concentration?

Accepted Answer

$0.125\ \mathrm{M}$

Question 9

Which of the following compounds is a strong electrolyte when dissolved in water?

Accepted Answer

$\mathrm{NaCl}$

Question 10

Which of the following is the correct oxidation number for sulfur in $\mathrm{SO_2}$?

Accepted Answer

$+4$

Question 11

In a titration, $25.0\ \mathrm{mL}$ of $0.100\ \mathrm{M}$ $\mathrm{NaOH}$ is required to neutralize $50.0\ \mathrm{mL}$ of $\mathrm{HCl}$. What is the concentration of the $\mathrm{HCl}$ solution?

Accepted Answer

$0.050\ \mathrm{M}$

Question 12

Which of the following reactions is a precipitation reaction?

Accepted Answer

$\mathrm{BaCl_2} (aq) + \mathrm{Na_2SO_4} (aq) \rightarrow \mathrm{BaSO_4} (s) + 2\mathrm{NaCl} (aq)$

Question 13

Which of the following is the correct formula for the molecular compound dinitrogen tetroxide?

Accepted Answer

$\mathrm{N_2O_4}$

Question 14

A $0.10\ \mathrm{M}$ solution of $\mathrm{CaCl_2}$ is prepared. What is the concentration of $\mathrm{Cl^-}$ ions?

Accepted Answer

$0.20\ \mathrm{M}$

Question 15

Which of the following is the correct net ionic equation for the neutralization of $\mathrm{HNO_3}$ with $\mathrm{NaOH}$?

Accepted Answer

$\mathrm{H^+} (aq) + \mathrm{OH^-} (aq) \rightarrow \mathrm{H_2O} (l)$

Question 16

Which of the following is a redox reaction?

Accepted Answer

$\mathrm{Zn} (s) + \mathrm{CuSO_4} (aq) \rightarrow \mathrm{Cu} (s) + \mathrm{ZnSO_4} (aq)$

Question 17

Which of the following is the correct formula for calculating molarity ($M$)?

Accepted Answer

$M = \frac{	ext{moles of solute}}{	ext{liters of solution}}$

Question 18

A $50.0\ \mathrm{mL}$ sample of $0.20\ \mathrm{M}$ $\mathrm{K_2SO_4}$ is diluted to $200.0\ \mathrm{mL}$. What is the final concentration?

Accepted Answer

$0.050\ \mathrm{M}$

Question 19

Which of the following best describes the role of the reducing agent in a redox reaction?

Accepted Answer

It donates electrons and is oxidized.

Exam 2 Study Guide: Mass Relationships and Reactions in Aqueous Solution

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