Q: Suppose that 25 g of gold, silver, aluminum, and water are each initially at 27.0°C. What is the final temperature of each substance upon absorbing 2.35 kJ of heat? (Given: $$c_{Au} = 0.129\ \text{J/g} \cdot \text{°C}$$, $$c_{Ag} = 0.235\ \text{J/g} \cdot \text{°C}$$, $$c_{Al} = 0.897\ \text{J/g} \cdot \text{°C}$$, $$c_{H_2O} = 4.18\ \text{J/g} \cdot \text{°C})$$

Gold: $$T_f = 27.0 + \frac{2350}{25 \times 0.129} = 27.0 + 729 = 756.0\ \text{°C}$$

Q: When 1 mol of a fuel burns at constant pressure, it produces 3452 kJ of heat and does 11 kJ of work. What are $$\Delta E$$ and $$\Delta H$$ for the combustion of the fuel?

$$\Delta E = -3463\ \text{kJ},\ \Delta H = -3452\ \text{kJ}$$

Q: What is the de Broglie wavelength of an electron traveling at $$1.35 \times 10^5$\ \text{m/s}$$? ($$m_e = 9.11 \times 10$$^{-31}$$\ \text{kg}$$, $$h = 6.626 \times 10$$^{-34}$$\ \text{J} \cdot \text{s})$$

$$\lambda = \frac{h}{mv} = \frac{6.626 \times 10$$^{-34}$$}{9.11 \times 10$$^{-31}$$ \times 1.35 \times 10^5$} = 5.36 \times 10$$^{-9}$$\ \text{m}$$

Question 1

A system releases 622 kJ of heat and does 105 kJ of work on the surroundings. What is the change in internal energy of the system?

Accepted Answer

$$\Delta E = -727\ 	ext{kJ}$$

Question 2

Which statement correctly describes an exothermic process?

Accepted Answer

The internal energy of the system decreases and the internal energy of the surroundings increases.

Question 3

How much heat is required to warm 1.50 L of water from 25.0°C to 100.0°C? (Assume a density of 1.0 g/mL for the water and $$c = 4.18\ 	ext{J/g} \cdot 	ext{°C})$$

Accepted Answer

$$Q = 46950\ 	ext{J}$$

Question 4

Suppose that 25 g of gold, silver, aluminum, and water are each initially at 27.0°C. What is the final temperature of each substance upon absorbing 2.35 kJ of heat? (Given: $$c_{Au} = 0.129\ 	ext{J/g} \cdot 	ext{°C}$$, $$c_{Ag} = 0.235\ 	ext{J/g} \cdot 	ext{°C}$$, $$c_{Al} = 0.897\ 	ext{J/g} \cdot 	ext{°C}$$, $$c_{H_2O} = 4.18\ 	ext{J/g} \cdot 	ext{°C})$$

Accepted Answer

Gold: $$T_f = 27.0 + \frac{2350}{25 	imes 0.129} = 27.0 + 729 = 756.0\ 	ext{°C}$$

Question 5

When 1 mol of a fuel burns at constant pressure, it produces 3452 kJ of heat and does 11 kJ of work. What are $$\Delta E$$ and $$\Delta H$$ for the combustion of the fuel?

Accepted Answer

$$\Delta E = -3463\ 	ext{kJ},\ \Delta H = -3452\ 	ext{kJ}$$

Question 6

Determine whether each process is exothermic or endothermic and indicate the sign of $$\Delta H$$: a) natural gas burning on a stove, b) isopropyl alcohol evaporating from skin, c) water condensing from steam.

Accepted Answer

a) Exothermic, $$\Delta H  0$$; c) Exothermic, $$\Delta H \u003c 0$$

Question 7

If a bottle of nail polish remover contains 177 mL of acetone ($$	ext{C}_3	ext{H}_6	ext{O}$$), how much heat is released by its complete combustion? ($$\Delta H_{rxn} = -1790\ 	ext{kJ}$$, density = 0.788 g/mL, molar mass = 58.08 g/mol)

Accepted Answer

$$Q = -4290\ 	ext{kJ}$$

Question 8

List these types of electromagnetic radiation in order of (i) increasing frequency and (ii) decreasing energy per photon: gamma rays, radio waves, microwaves, visible light.

Accepted Answer

Increasing frequency: radio waves  visible light \u003e microwaves \u003e radio waves

Question 9

What is the de Broglie wavelength of an electron traveling at $$1.35 	imes 10^5$\ 	ext{m/s}$$? ($$m_e = 9.11 	imes 10$$^{-31}$$\ 	ext{kg}$$, $$h = 6.626 	imes 10$$^{-34}$$\ 	ext{J} \cdot 	ext{s})$$

Accepted Answer

$$\lambda = \frac{h}{mv} = \frac{6.626 	imes 10$$^{-34}$$}{9.11 	imes 10$$^{-31}$$ 	imes 1.35 	imes 10^5$} = 5.36 	imes 10$$^{-9}$$\ 	ext{m}$$

Question 10

Which electron is, on average, closer to the nucleus: an electron in a 2s orbital or an electron in a 3s orbital?

Accepted Answer

An electron in a 2s orbital

Question 11

What are the possible values of $$l$$ for $$n = 3$$?

Accepted Answer

$$l = 0, 1, 2$$

Question 12

What are the possible values of $$m_l$$ for $$l = 2$$?

Accepted Answer

$$m_l = -2, -1, 0, 1, 2$$

Question 13

According to the quantum-mechanical model for the hydrogen atom, which electron transition produces light with the longer wavelength: $$2p \rightarrow 1s or$$ $$3p \rightarrow 1s$$?

Accepted Answer

$$2p \rightarrow 1s$$

Question 14

Arrange these elements in order of increasing atomic radius: Ca, Rb, S, Si, Ge, F.

Accepted Answer

F \u003c S \u003c Si \u003c Ge \u003c Ca \u003c Rb

Question 15

Choose the element with the higher first ionization energy from each pair: a) Br or Bi, b) Na or Rb, c) As or At, d) P or Sn.

Accepted Answer

Br, Na, As, P

Question 16

Choose the element with the more negative (more exothermic) electron affinity from each pair: a) Na or Rb, b) B or S, c) C or N, d) Li or F.

Accepted Answer

Na, S, C, F

Question 17

Which outer electron configuration would you expect to belong to a reactive nonmetal?

Accepted Answer

$$ns^2np^5$

General Chemistry Study Guide: Thermochemistry, Quantum Chemistry, and Periodic Trends

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