Q: A sample of oxygen gas is collected over water at 25°C. The total pressure in the container is 755 mm Hg, and the vapor pressure of water at 25°C is 23.8 mm Hg. What is the partial pressure of the oxygen gas?

$$755\ \text{mm Hg} - 23.8\ \text{mm Hg} = 731.2\ \text{mm Hg}$$

Q: Which molecule below is always nonpolar, regardless of the atoms involved?

A linear molecule with the general formula $$\text{A}_2\text{X}$$

Q: A 2.00 L container holds 0.080 mol of nitrogen gas at 27°C. What is the pressure in the container? (Use $$R = 0.0821\ \text{L} \cdot \text{atm} / \text{mol} \cdot \text{K})$$

$$P = \frac{nRT}{V} = \frac{0.080 \times 0.0821 \times 300}{2.00} = 0.984\ \text{atm}$$

Q: A mixture contains 2.0 mol of $$\text{O}_2$$ and 3.0 mol of $$\text{N}_2 in a $$container at a total pressure of 5.0 atm. What is the partial pressure of $$\text{O}_2$$?

$$P_{O_2$} = X_{O_2$} \times P_{\text{total}} = \frac{2.0}{2.0+3.0} \times 5.0 = 2.0\ \text{atm}$$

Q: A gas sample has a density of $$1.25\ \text{g/L} at$$ $$2.00\ \text{atm}$$ and $$273\ \text{K}. $$What is the molar mass of the gas?

$$M = \frac{dRT}{P} = \frac{1.25 \times 0.0821 \times 273}{2.00} = 14.0\ \text{g/mol}$$

Q: A gas sample at 1.00 atm and 273 K occupies 22.4 L. If the pressure is doubled and the temperature is kept constant, what will be the new volume?

$$V_2$$ = \frac{P_1V_1}{$$P_2$$} = \frac{1.00 \times 22.4}{2.00} = 11.2\ \text{L}$$

Question 1

Which of the following statements best explains why noble gases do not have electronegativity values assigned?

Accepted Answer

Noble gases generally do not form compounds because they have a stable octet and do not share electrons.

Question 2

A sample of oxygen gas is collected over water at 25°C. The total pressure in the container is 755 mm Hg, and the vapor pressure of water at 25°C is 23.8 mm Hg. What is the partial pressure of the oxygen gas?

Accepted Answer

$$755\ 	ext{mm Hg} - 23.8\ 	ext{mm Hg} = 731.2\ 	ext{mm Hg}$$

Question 3

Which molecule below is always nonpolar, regardless of the atoms involved?

Accepted Answer

A linear molecule with the general formula $$	ext{A}_2	ext{X}$$

Question 4

Which of the following best describes the difference between sigma ($$\sigma) $$and pi ($$\pi) $$bonds?

Accepted Answer

Sigma bonds are formed from end-to-end overlap of orbitals, while pi bonds are formed from sideways overlap of unhybridized p orbitals.

Question 5

A 2.00 L container holds 0.080 mol of nitrogen gas at 27°C. What is the pressure in the container? (Use $$R = 0.0821\ 	ext{L} \cdot 	ext{atm} / 	ext{mol} \cdot 	ext{K})$$

Accepted Answer

$$P = \frac{nRT}{V} = \frac{0.080 	imes 0.0821 	imes 300}{2.00} = 0.984\ 	ext{atm}$$

Question 6

Which of the following molecules violates the octet rule by having fewer than eight electrons around the central atom?

Accepted Answer

$$	ext{BeCl}_2$$

Question 7

Which statement about bond enthalpy and bond length is correct?

Accepted Answer

Single bonds are longer and have lower bond enthalpy than double bonds.

Question 8

A mixture contains 2.0 mol of $$	ext{O}_2$$ and 3.0 mol of $$	ext{N}_2 in a $$container at a total pressure of 5.0 atm. What is the partial pressure of $$	ext{O}_2$$?

Accepted Answer

$$P_{O_2$} = X_{O_2$} 	imes P_{	ext{total}} = \frac{2.0}{2.0+3.0} 	imes 5.0 = 2.0\ 	ext{atm}$$

Question 9

Which of the following best describes the molecular geometry of $$	ext{SF}_6$$?

Accepted Answer

Octahedral

Question 10

Which element is the most electronegative?

Accepted Answer

Fluorine

Question 11

A gas sample has a density of $$1.25\ 	ext{g/L} at$$ $$2.00\ 	ext{atm}$$ and $$273\ 	ext{K}. $$What is the molar mass of the gas?

Accepted Answer

$$M = \frac{dRT}{P} = \frac{1.25 	imes 0.0821 	imes 273}{2.00} = 14.0\ 	ext{g/mol}$$

Question 12

Which of the following molecules has delocalized $$\pi$$ bonding?

Accepted Answer

$$	ext{O}_3 ($$ozone)

Question 13

Which of the following is NOT a characteristic property of gases?

Accepted Answer

Gases have strong intermolecular forces.

Question 14

Which hybridization corresponds to a central atom with three electron domains?

Accepted Answer

$$sp^2$$

Question 15

A gas sample at 1.00 atm and 273 K occupies 22.4 L. If the pressure is doubled and the temperature is kept constant, what will be the new volume?

Accepted Answer

$$V_2$$ = \frac{P_1V_1}{$$P_2$$} = \frac{1.00 	imes 22.4}{2.00} = 11.2\ 	ext{L}$$

Question 16

Which of the following statements about the kinetic-molecular theory is correct?

Accepted Answer

Gas molecules are far apart and move rapidly, so intermolecular forces are negligible.

Question 17

Which of the following molecules is expected to be polar due to its shape, even though it contains polar bonds?

Accepted Answer

$$	ext{H}_2	ext{O}$$

Question 18

Which of the following is the correct formula for formal charge?

Accepted Answer

$$	ext{Formal charge} = 	ext{valence electrons in free atom} - [	ext{non-bonding electrons} + \frac{1}{2} 	ext{bonding electrons}]$$

Question 19

According to the gas laws, what happens to the pressure of a gas if its temperature is increased at constant volume?

Accepted Answer

The pressure increases because the molecules move faster and collide more forcefully with the container walls.

Question 20

Which of the following pairs of elements is most likely to form an ionic bond?

Accepted Answer

Sodium and chlorine

General Chemistry Study Guide: Chemical Bonding, Molecular Geometry, and Gases

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