Q: A rigid container holds 2.0 moles of Ar(g) at 45.0°C. The pressure is 1.05 atm. What is the volume of the container in liters? (Use $$R = 0.0821\ \mathrm{L\cdot atm\cdot $$mol^{-1}$$\cdot K$$^{-1}$$})$$

$$V = \dfrac{nRT}{P} = \dfrac{2.0 \times 0.0821 \times 318.15}{1.05} \approx 49.7\ \mathrm{L}$$

Q: A 3.00 L sample of helium gas is stored at 25°C at a pressure of 2.00 bar. If the temperature is increased to 50°C at constant volume, what is the new pressure?

$$P_2$$ = $$P_1$$ \dfrac{$$T_2$$}{$$T_1$$} = 2.00 \times \dfrac{323.15}{298.15} \approx 2.17\ \mathrm{bar}$$

Q: A rigid container is filled with 2.5 mol of O$$_2$$, 3.5 mol of N$$_2$$, and 1.5 mol of H$$_2. $$What is the partial pressure of N$$_2 if $$the total pressure is 5.0 atm?

$$P_{N_2$} = 5.0 \times \dfrac{3.5}{2.5+3.5+1.5} = 5.0 \times \dfrac{3.5}{7.5} \approx 2.33\ \mathrm{atm}$$

Question 1

Which of the following best describes the type of bond formed in NaCl?

Accepted Answer

Ionic bond formed by transfer of electrons from Na to Cl.

Question 2

Consider the reaction: $$\mathrm{NaOH} + \mathrm{HCl} \rightarrow \mathrm{NaCl} + \mathrm{H_2O}. $$Which species acts as the acid?

Accepted Answer

HCl

Question 3

Which of the following statements about gases is TRUE?

Accepted Answer

At constant volume, increasing the temperature of a gas will increase its pressure.

Question 4

A rigid container holds 2.0 moles of Ar(g) at 45.0°C. The pressure is 1.05 atm. What is the volume of the container in liters? (Use $$R = 0.0821\ \mathrm{L\cdot atm\cdot $$mol^{-1}$$\cdot K$$^{-1}$$})$$

Accepted Answer

$$V = \dfrac{nRT}{P} = \dfrac{2.0 	imes 0.0821 	imes 318.15}{1.05} \approx 49.7\ \mathrm{L}$$

Question 5

Which gas sample will have the largest root mean square speed at the same temperature?

Accepted Answer

H$$_2 at 25$$°C

Question 6

A sample of gas molecules is added to a rigid container at constant temperature. Which sample will result in the smallest pressure?

Accepted Answer

32.0 g of O$$_2$$

Question 7

A 3.00 L sample of helium gas is stored at 25°C at a pressure of 2.00 bar. If the temperature is increased to 50°C at constant volume, what is the new pressure?

Accepted Answer

$$P_2$$ = $$P_1$$ \dfrac{$$T_2$$}{$$T_1$$} = 2.00 	imes \dfrac{323.15}{298.15} \approx 2.17\ \mathrm{bar}$$

Question 8

Which of the following is the correct net ionic equation for the reaction between NaOH(aq) and HCl(aq)?

Accepted Answer

$$\mathrm{OH^-} + \mathrm{H^+} \rightarrow \mathrm{H_2O}$$

Question 9

A rigid container is filled with 2.5 mol of O$$_2$$, 3.5 mol of N$$_2$$, and 1.5 mol of H$$_2. $$What is the partial pressure of N$$_2 if $$the total pressure is 5.0 atm?

Accepted Answer

$$P_{N_2$} = 5.0 	imes \dfrac{3.5}{2.5+3.5+1.5} = 5.0 	imes \dfrac{3.5}{7.5} \approx 2.33\ \mathrm{atm}$$

Question 10

Which of the following reactions is responsible for acid rain in Earth's atmosphere?

Accepted Answer

$$2\mathrm{SO_2$}(g) + 2\mathrm{H_2O}(l) + \mathrm{O_2$}(g) \rightarrow 2\mathrm{H_2SO_4}(aq)$$

Question 11

A sample contains 0.50 mol of H$$_2$$, 2.5 mol of O$$_2$$, and 1.0 mol of N$$_2. $$What is the mole fraction of O$$_2$$?

Accepted Answer

$$X_{O_2$} = \dfrac{2.5}{0.5+2.5+1.0} = \dfrac{2.5}{4.0} = 0.625$$

Question 12

A sealed flask is placed on the roof of a container. If it takes 230 seconds for 10.0 mL of Ar(g) to escape the container, how much time (in seconds) will it take for the same volume of H$$_2(g) to $$escape under identical conditions?

Accepted Answer

$$t_{H_2$} = t_{Ar} \sqrt{\dfrac{M_{H_2$}}{M_{Ar}}} = 230 \sqrt{\dfrac{2.0}{39.9}} \approx 72.6\ \mathrm{s}$$

Question 13

Which of the following best describes the limiting reactant in a chemical reaction?

Accepted Answer

The reactant that is completely consumed first, limiting the amount of product formed.

Question 14

A solution is prepared by mixing 50.0 mL of 0.200 M NaOH with 50.0 mL of 0.100 M HCl. What is the final concentration of Na$$^+$$ ions in the solution?

Accepted Answer

$$[\mathrm{Na^+}] = \dfrac{0.200 	imes 50.0}{100.0} = 0.100\ \mathrm{M}$$

Question 15

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

Accepted Answer

$$	ext{Percent NaCl} = \dfrac{	ext{mass of NaCl}}{	ext{total mass of solution}} 	imes 100$$

Question 16

Which of the following is a correct statement about the relationship between pressure and volume for a gas at constant temperature?

Accepted Answer

Pressure and volume are inversely proportional.

Question 17

A rigid container is filled with a mixture of O$$_2$$ and N$$_2. If $$the pressure in the container is 2.5 atm and the mole fraction of O$$_2 is 0.40$$, what is the partial pressure of O$$_2$$?

Accepted Answer

$$P_{O_2$} = 2.5 	imes 0.40 = 1.0\ \mathrm{atm}$$

Question 18

Which of the following best explains why H$$_2$$ gas effuses faster than O$$_2$$ gas under identical conditions?

Accepted Answer

H$$_2$$ has a lower molar mass than O$$_2$$, so its molecules move faster.

General Chemistry: Chemical Reactions, Gases, and Stoichiometry – Practice Quiz Study Notes

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