Q: A 2.00 mol sample of an ideal gas is contained in a 10.0 L vessel at 300 K. What is the pressure of the gas in atmospheres? (Use $$R = 0.0821 \text{ L} \cdot \text{atm} / \text{mol} \cdot \text{K})$$

$$P = \dfrac{nRT}{V} = \dfrac{2.00 \times 0.0821 \times 300}{10.0} = 4.93 \text{ atm}$$

Q: A mixture contains 2.0 mol of O$$_2$$ and 3.0 mol of N$$_2 in a 5.0 L $$container at 400 K. What is the partial pressure of N$$_2$$? ($$R = 0.0821 \text{ L} \cdot \text{atm} / \text{mol} \cdot \text{K})$$

$$P_{N_2$} = \dfrac{n$$_{N_2}$$RT}{V} = \dfrac{3.0 \times 0.0821 \times 400}{5.0} = 19.7 \text{ atm}$$

Q: Calculate the heat required to raise the temperature of 100 g of water from 25°C to 75°C. (Specific heat capacity of water $$c = 4.18 \text{ J/g} \cdot \text{K})$$

$$q = mc\Delta T = 100 \times 4.18 \times (75-25) = 20,900 \text{ J}$$

Question 1

A 2.00 mol sample of an ideal gas is contained in a 10.0 L vessel at 300 K. What is the pressure of the gas in atmospheres? (Use $$R = 0.0821 	ext{ L} \cdot 	ext{atm} / 	ext{mol} \cdot 	ext{K})$$

Accepted Answer

$$P = \dfrac{nRT}{V} = \dfrac{2.00 	imes 0.0821 	imes 300}{10.0} = 4.93 	ext{ atm}$$

Question 2

Which statement best explains why real gases deviate from ideal behavior at high pressures?

Accepted Answer

Intermolecular forces and the finite volume of gas particles become significant.

Question 3

A mixture contains 2.0 mol of O$$_2$$ and 3.0 mol of N$$_2 in a 5.0 L $$container at 400 K. What is the partial pressure of N$$_2$$? ($$R = 0.0821 	ext{ L} \cdot 	ext{atm} / 	ext{mol} \cdot 	ext{K})$$

Accepted Answer

$$P_{N_2$} = \dfrac{n$$_{N_2}$$RT}{V} = \dfrac{3.0 	imes 0.0821 	imes 400}{5.0} = 19.7 	ext{ atm}$$

Question 4

Which of the following gases will effuse fastest under identical conditions according to Graham's Law?

Accepted Answer

Hydrogen ($$H_2)$$

Question 5

A sample of gas at 273 K has a root mean square velocity ($$u_{rms}) of$$ $$1.50 	imes 10^3$ 	ext{ m/s}. If $$the temperature is doubled, what happens to $$u_{rms}$$?

Accepted Answer

$$u_{rms}$$ increases by a factor of $$\sqrt{2}$$

Question 6

Which equation best represents the relationship between the kinetic energy of a gas molecule and temperature?

Accepted Answer

$$KE_{avg} = \dfrac{3}{2}RT$$

Question 7

A 1.00 g sample of helium ($$He) $$and a 1.00 g sample of oxygen ($$O_2) $$are placed in identical containers at the same temperature. Which statement is true?

Accepted Answer

Helium atoms have a higher average speed than oxygen molecules.

Question 8

Which of the following best describes the first law of thermodynamics?

Accepted Answer

Energy cannot be created or destroyed, only transferred or transformed.

Question 9

A chemical reaction in a bomb calorimeter releases 500 kJ of heat. What is the value of $$q_{cal}$$?

Accepted Answer

$$q_{cal} = +500 	ext{ kJ}$$

Question 10

Which of the following is an example of an endothermic process?

Accepted Answer

Melting ice to form liquid water

Question 11

Calculate the heat required to raise the temperature of 100 g of water from 25°C to 75°C. (Specific heat capacity of water $$c = 4.18 	ext{ J/g} \cdot 	ext{K})$$

Accepted Answer

$$q = mc\Delta T = 100 	imes 4.18 	imes (75-25) = 20,900 	ext{ J}$$

Question 12

Which equation correctly relates enthalpy change ($$\Delta H) to $$internal energy change ($$\Delta E$$), pressure ($$P$$), and volume change ($$\Delta V$$)?

Accepted Answer

$$\Delta H = \Delta E + P\Delta V$$

Question 13

Which statement about the quantum-mechanical model of the atom is correct?

Accepted Answer

It describes electrons as occupying orbitals defined by probability distributions.

Question 14

What is the energy of a photon with a wavelength of $$500 	ext{ nm}$$? ($$h = 6.626 	imes 10$$^{-34}$$ 	ext{ J} \cdot 	ext{s}$$, $$c = 3.00 	imes 10^8$ 	ext{ m/s})$$

Accepted Answer

$$E = \dfrac{hc}{\lambda} = \dfrac{6.626 	imes 10$$^{-34}$$ 	imes 3.00 	imes 10^8$}{500 	imes 10$$^{-9}$$} = 3.98 	imes 10$$^{-19}$$ 	ext{ J}$$

Question 15

According to the Heisenberg Uncertainty Principle, which of the following is true?

Accepted Answer

It is impossible to simultaneously know both the exact position and momentum of an electron.

Question 16

Which quantum number determines the shape of an atomic orbital?

Accepted Answer

Angular momentum quantum number ($$l)$$

Question 17

Which of the following transitions in the hydrogen atom will emit the highest energy photon?

Accepted Answer

From $$n=3 to$$ $$n=1$$

Question 18

Which statement best describes the difference between $$s$$ and $$p$$ orbitals?

Accepted Answer

$$s$$ orbitals are spherical, while $$p$$ orbitals are dumbbell-shaped.

Question 19

Which equation is used to calculate the wavelength of a particle according to de Broglie?

Accepted Answer

$$\lambda = \dfrac{h}{mv}$$

General Chemistry Study Guide: Gases, Thermochemistry, and Quantum-Mechanical Model of the Atom

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