Question 1

A sample of magnesium chloride hexahydrate ($$\mathrm{$$MgCl_2$$ \cdot 6H_2O}) is $$heated to drive off the water. If the original mass of the hydrate is 10.0 g and the mass after heating is 4.8 g, what is the number of moles of water lost?

Accepted Answer

$$0.288$$ mol

Question 2

Which of the following statements best explains why the formation of a chemical bond lowers the potential energy of a molecule?

Accepted Answer

Attractive forces between atoms outweigh repulsive forces, resulting in a more stable, lower-energy arrangement.

Question 3

A 2.00 L sample of nitrogen gas at $$25^\circ\mathrm{C}$$ and $$1.00$$ atm is compressed to $$1.00 L at $$constant temperature. What is the final pressure of the gas?

Accepted Answer

$$2.00$$ atm

Question 4

Which of the following compounds contains both ionic and covalent bonds?

Accepted Answer

$$\mathrm{$$NaNO_3$$}$$

Question 5

Which of the following best describes the difference between an empirical formula and a molecular formula?

Accepted Answer

The empirical formula shows the simplest whole-number ratio of atoms, while the molecular formula shows the actual number of atoms in a molecule.

Question 6

A student dissolves $$0.50$$ mol of $$\mathrm{NaCl} in $$enough water to make $$1.0 L of $$solution. What is the concentration of chloride ions in the solution?

Accepted Answer

$$0.50 M$$

Question 7

Which of the following best explains why water has a higher boiling point than methane ($$\mathrm{CH_4$}$$)?

Accepted Answer

Water molecules form hydrogen bonds, which are much stronger than the London dispersion forces in methane.

Question 8

Which of the following electron configurations represents a calcium ion ($$\mathrm{Ca$$^{2+}$$}$$)?

Accepted Answer

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

Question 9

A $$0.100 M $$solution of acetic acid ($$\mathrm{CH_3COOH}) $$has a pH of $$2.9. $$Which of the following best describes acetic acid?

Accepted Answer

It is a weak acid because it only partially ionizes in water.

Question 10

Which of the following statements about the electromagnetic spectrum is correct?

Accepted Answer

Ultraviolet light has a shorter wavelength and higher energy than visible light.

Question 11

A $$5.00 g $$sample of an unknown gas occupies $$2.00 L at$$ $$1.00$$ atm and $$273 K. $$What is the molar mass of the gas? (Use $$R = 0.0821\ \mathrm{L\cdot atm\cdot $$mol^{-1}$$\cdot K$$^{-1}$$})$$

Accepted Answer

$$56.0\ \mathrm{g\cdot $$mol^{-1}$$}$$

Question 12

Which of the following molecules is nonpolar, even though it contains polar bonds?

Accepted Answer

$$\mathrm{CO_2$}$$

Question 13

Which of the following best describes the trend in atomic radius as you move down a group in the periodic table?

Accepted Answer

Atomic radius increases due to the addition of energy levels.

Question 14

A solution is prepared by diluting $$50.0 mL of$$ $$6.00 M$$ $$\mathrm{HCl} to a $$final volume of $$300.0 mL. $$What is the final concentration?

Accepted Answer

$$1.00 M$$

Question 15

Which of the following best explains why ionic solids have higher melting points than molecular solids?

Accepted Answer

Ionic solids are held together by strong electrostatic forces between ions, while molecular solids are held together by weaker intermolecular forces.

Question 16

Which of the following is the correct balanced equation for the neutralization of sulfuric acid ($$\mathrm{H_2SO_4}) $$with sodium hydroxide ($$\mathrm{NaOH}$$)?

Accepted Answer

$$\mathrm{H_2SO_4} + 2\mathrm{NaOH} \rightarrow 2\mathrm{H_2O} + \mathrm{Na_2SO_4}$$

Question 17

Which of the following best describes the process that creates atomic spectra?

Accepted Answer

Electrons absorb energy and move to higher energy levels, then emit photons as they return to lower levels.

Question 18

A $$25.0 mL $$sample of $$0.200 M$$ $$\mathrm{NaOH} is $$required to neutralize $$50.0 mL of an$$ $$\mathrm{HCl}$$ solution. What is the concentration of the $$\mathrm{HCl}$$ solution?

Accepted Answer

$$0.100 M$$

Question 19

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

Accepted Answer

Gas particles are in constant, random motion and collisions between them are elastic.

Question 20

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

Accepted Answer

As temperature increases, pressure increases, provided the volume and number of moles are constant.

Honors Chemistry Second Semester Exam Study Guide: Key Concepts and Applications

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