Q: Which of the following statements best describes the concept of a mole in chemistry?

A mole is the amount of substance that contains $$6.022 \times 10$$^{23}$$ particles.

Question 1

Which of the following statements best describes the concept of a mole in chemistry?

Accepted Answer

A mole is the amount of substance that contains $$6.022 	imes 10$$^{23}$$ particles.

Question 2

Calculate the mass of $$2.50$$ moles of $$\mathrm{CO_2$} ($$carbon dioxide). (Molar mass of $$\mathrm{CO_2$} = 44.0\ \mathrm{g/mol})$$

Accepted Answer

$$110\ \mathrm{g}$$

Question 3

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

Accepted Answer

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

Question 4

A reaction absorbs $$150\ \mathrm{kJ} of $$energy from its surroundings. Which term best describes this reaction?

Accepted Answer

Endothermic

Question 5

Which of the following best describes a synthesis (combination) reaction?

Accepted Answer

$$A + B \rightarrow AB$$

Question 6

A sample of gas has a volume of $$2.0\ \mathrm{L} at$$ $$1.0\ \mathrm{atm}. If $$the pressure is increased to $$4.0\ \mathrm{atm} at $$constant temperature, what is the new volume? (Boyle’s Law: $$P_1V_1 = P_2V_2)$$

Accepted Answer

$$0.50\ \mathrm{L}$$

Question 7

Which of the following statements is NOT a postulate of the kinetic molecular theory of gases?

Accepted Answer

Gas particles lose energy during collisions.

Question 8

A $$500.0\ \mathrm{mL}$$ sample of gas at $$25^\circ\mathrm{C} is $$heated to $$75^\circ\mathrm{C} at $$constant pressure. What is the new volume? (Charles’s Law: $$\frac{V_1$}{T_1$} = \frac{V_2$}{T_2$}$$, temperatures in Kelvin)

Accepted Answer

$$583\ \mathrm{mL}$$

Question 9

Which of the following best describes a solution?

Accepted Answer

A homogeneous mixture of two or more substances

Question 10

Which of the following is an example of an electrolyte?

Accepted Answer

$$\mathrm{NaCl} ($$sodium chloride) dissolved in water

Question 11

A $$100.0\ \mathrm{g}$$ solution contains $$5.0\ \mathrm{g} of$$ $$\mathrm{NaCl}. $$What is the mass percent of $$\mathrm{NaCl} in $$the solution?

Accepted Answer

$$5.0\%$$

Question 12

Which of the following best describes a hypertonic solution relative to a cell?

Accepted Answer

The solution has a higher solute concentration than the cell.

Question 13

Which law explains why a balloon shrinks when placed in a freezer?

Accepted Answer

Charles’s Law

Question 14

A $$2.0\ \mathrm{L}$$ solution contains $$0.5\ \mathrm{mol} of$$ $$\mathrm{NaOH}. $$What is the molarity of the solution?

Accepted Answer

$$0.25\ \mathrm{M}$$

Question 15

Which of the following mixtures is a colloid?

Accepted Answer

Milk

Question 16

A patient receives an intravenous (IV) solution that is hypotonic relative to their blood cells. What is the most likely effect on the cells?

Accepted Answer

The cells will swell and may burst.

Question 17

Which of the following is true about the relationship between solubility and temperature for most solid solutes in water?

Accepted Answer

Solubility increases as temperature increases.

Question 18

A mixture of gases contains $$2.0\ \mathrm{atm} of$$ $$\mathrm{O_2$}$$, $$1.0\ \mathrm{atm} of$$ $$\mathrm{N_2$}$$, and $$0.5\ \mathrm{atm} of$$ $$\mathrm{CO_2$}. $$What is the total pressure according to Dalton’s Law?

Accepted Answer

$$3.5\ \mathrm{atm}$$

Question 19

Which of the following best describes an unsaturated solution?

Accepted Answer

A solution that can dissolve more solute at a given temperature.

Question 20

A $$250\ \mathrm{mL}$$ sample of gas at $$1.0\ \mathrm{atm}$$ and $$300\ \mathrm{K} is $$compressed to $$125\ \mathrm{mL}$$ and heated to $$600\ \mathrm{K}. $$What is the new pressure? (Combined Gas Law: $$\frac{P_1V_1}{T_1$} = \frac{P_2V_2}{T_2$})$$

Accepted Answer

$$2.0\ \mathrm{atm}$$

Exam 2 Review: Chemical Reactions, Gases, and Solutions

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