Q: A student mixes two solutions in a calorimeter and observes a temperature increase of $$4.5\ ^\circ\mathrm{C}. If $$the mass of the solution is $$100\ \mathrm{g}$$ and the specific heat capacity is $$4.18\ \mathrm{J}/\mathrm{g}\cdot\ ^\circ\mathrm{C}$$, what is the heat absorbed by the solution?

$$Q = 100 \times 4.18 \times 4.5 = 1881\ \mathrm{J}$$

Q: Which of the following is the correct form of Hess's Law?

$$\Delta H_{\text{reaction}} = \Delta H_{1} + \Delta H_{2} + \Delta H_{3}$$

Q: Given the following enthalpies of formation: $$\Delta H_f(\mathrm{CO}_2) = -393.5\ \mathrm{kJ/mol}$$, $$\Delta H_f(\mathrm{H}_2O) = -285.8\ \mathrm{kJ/mol}$$, $$\Delta H_f(\mathrm{C}_6H_{12}O_6$) = -1273.3\ \mathrm{kJ/mol}$$, calculate $$\Delta H_{\text{reaction}}$$ for the combustion of glucose: $$\mathrm{C}_6H_{12}O_6$ + 6\mathrm{O}_2 \rightarrow 6\mathrm{CO}_2 + 6\mathrm{H}_2O.$$

$$\Delta H_{\text{reaction}} = [6(-393.5) + 6(-285.8)] - [-1273.3] = -2808.6\ \mathrm{kJ}$$

Q: Using the Rydberg equation $$\frac{1}{\lambda} = R_H \left( \frac{1}{n_1$^2} - \frac{1}{n_2$^2} \right)$$, what is the wavelength of light emitted when an electron in a hydrogen atom transitions from $$n_2 = 3$ to n_1$ = 2$$? ($$R_H = 1.097 \times 10^7$\ \mathrm{m}^{-1})$$

$$\lambda = \frac{1}{1.097 \times 10^7$ \left( \frac{1}{4} - \frac{1}{9} \right)} = 6.56 \times 10$$^{-7}$$\ \mathrm{m}$$

Q: Which of the following best explains why atomic radius decreases across a period?

Effective nuclear charge ($$Z_{\text{eff}}) $$increases, pulling electrons closer to the nucleus.

Question 1

Which of the following best describes an endothermic reaction?

Accepted Answer

A reaction that absorbs heat from the surroundings, resulting in a temperature decrease.

Question 2

A student mixes two solutions in a calorimeter and observes a temperature increase of $$4.5\ ^\circ\mathrm{C}. If $$the mass of the solution is $$100\ \mathrm{g}$$ and the specific heat capacity is $$4.18\ \mathrm{J}/\mathrm{g}\cdot\ ^\circ\mathrm{C}$$, what is the heat absorbed by the solution?

Accepted Answer

$$Q = 100 	imes 4.18 	imes 4.5 = 1881\ \mathrm{J}$$

Question 3

Which of the following is the correct form of Hess's Law?

Accepted Answer

$$\Delta H_{	ext{reaction}} = \Delta H_{1} + \Delta H_{2} + \Delta H_{3}$$

Question 4

Given the following enthalpies of formation: $$\Delta H_f(\mathrm{CO}_2) = -393.5\ \mathrm{kJ/mol}$$, $$\Delta H_f(\mathrm{H}_2O) = -285.8\ \mathrm{kJ/mol}$$, $$\Delta H_f(\mathrm{C}_6H_{12}O_6$) = -1273.3\ \mathrm{kJ/mol}$$, calculate $$\Delta H_{	ext{reaction}}$$ for the combustion of glucose: $$\mathrm{C}_6H_{12}O_6$ + 6\mathrm{O}_2 ightarrow 6\mathrm{CO}_2 + 6\mathrm{H}_2O.$$

Accepted Answer

$$\Delta H_{	ext{reaction}} = [6(-393.5) + 6(-285.8)] - [-1273.3] = -2808.6\ \mathrm{kJ}$$

Question 5

The energy of a photon is related to its frequency by which equation?

Accepted Answer

$$E = h
u$$

Question 6

Using the Rydberg equation $$\frac{1}{\lambda} = R_H \left( \frac{1}{n_1$^2} - \frac{1}{n_2$^2} ight)$$, what is the wavelength of light emitted when an electron in a hydrogen atom transitions from $$n_2 = 3$ to n_1$ = 2$$? ($$R_H = 1.097 	imes 10^7$\ \mathrm{m}^{-1})$$

Accepted Answer

$$\lambda = \frac{1}{1.097 	imes 10^7$ \left( \frac{1}{4} - \frac{1}{9} ight)} = 6.56 	imes 10$$^{-7}$$\ \mathrm{m}$$

Question 7

Which quantum number determines the shape of an orbital?

Accepted Answer

Angular momentum quantum number $$l$$

Question 8

What is the electron configuration for the element phosphorus ($$Z=15$$)?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^2$$\ $$3p^3$$

Question 9

Which of the following best explains why atomic radius decreases across a period?

Accepted Answer

Effective nuclear charge ($$Z_{	ext{eff}}) $$increases, pulling electrons closer to the nucleus.

Question 10

Which element has the highest first ionization energy?

Accepted Answer

Neon ($$\mathrm{Ne})$$

Question 11

Which of the following ions has the largest radius?

Accepted Answer

$$\mathrm{O}^{2-}$$

Question 12

Which statement about electron affinity is correct?

Accepted Answer

Electron affinity generally becomes more negative across a period.

Question 13

Which of the following best describes a lattice energy?

Accepted Answer

The energy released when one mole of an ionic solid forms from its gaseous ions.

Question 14

Which step in the Born-Haber cycle involves the sublimation of a solid metal?

Accepted Answer

Conversion of the solid metal to a gaseous atom.

Question 15

Which of the following electron configurations represents a noble gas?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$

Question 16

Which of the following best describes the principle of the Bohr model?

Accepted Answer

Electrons move in fixed circular orbits around the nucleus with quantized energies.

Question 17

If an atom has quantum numbers $$n=3$$, $$l=2$$, $$m_l=0$$, what is the type of orbital?

Accepted Answer

$$3d$$

Question 18

Which of the following best explains why $$\mathrm{O}^{2-} is $$larger than $$\mathrm{F}^-$$?

Accepted Answer

$$\mathrm{O}^{2-}$$ has more electrons and a lower effective nuclear charge.

Question 19

Which of the following is the correct shorthand electron configuration for potassium ($$Z=19$$)?

Accepted Answer

$$[Ar]\ 4s^1$

Atomic Structure, Electron Configuration, and Periodic Trends: General Chemistry Study Notes

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