Q: Calculate the formula mass of calcium nitrate, $$\mathrm{Ca(NO}_3)_2. ($$Atomic masses: Ca = 40.08, N = 14.01, O = 16.00)

$$40.08 + 2 \times (14.01 + 3 \times 16.00) = 164.10\ \mathrm{amu}$$

Question 1

Which of the following statements best explains why water (H2O) has properties dramatically different from its constituent elements, hydrogen and oxygen?

Accepted Answer

When hydrogen and oxygen chemically combine to form water, a new substance with unique properties results due to the formation of covalent bonds.

Question 2

According to the law of definite proportions, which of the following is true for a sample of pure water?

Accepted Answer

Water always contains hydrogen and oxygen in a 2:1 atom ratio, regardless of the sample size.

Question 3

Which of the following best describes the difference between ionic and covalent bonds?

Accepted Answer

Ionic bonds involve the transfer of electrons from a metal to a nonmetal, while covalent bonds involve the sharing of electrons between nonmetals.

Question 4

Which of the following is the empirical formula for a compound with the molecular formula C6H12O6?

Accepted Answer

$$\mathrm{CH}_2\mathrm{O}$$

Question 5

A student is given a sample of a compound and determines it contains 24.5 g of nitrogen and 70.0 g of oxygen. What is the empirical formula of the compound? (Atomic masses: N = 14.01 g/mol, O = 16.00 g/mol)

Accepted Answer

$$\mathrm{N}_2\mathrm{O}_5$$

Question 6

Which of the following best explains why solid NaCl does not conduct electricity, but NaCl(aq) does?

Accepted Answer

In solid NaCl, the ions are locked in place and cannot move, but in aqueous solution, the ions are free to move and carry charge.

Question 7

What is the correct name for the compound FeCl3?

Accepted Answer

Iron(III) chloride

Question 8

Which of the following is the correct formula for aluminum nitride?

Accepted Answer

$$\mathrm{AlN}$$

Question 9

A hydrate of magnesium sulfate has the formula $$\mathrm{MgSO}_4 \cdot 7\mathrm{H}_2\mathrm{O}. $$What is the correct name for this compound?

Accepted Answer

Magnesium sulfate heptahydrate

Question 10

Which of the following is the correct name for the compound $$\mathrm{N}_2\mathrm{O}_5$$?

Accepted Answer

Dinitrogen pentoxide

Question 11

Calculate the formula mass of calcium nitrate, $$\mathrm{Ca(NO}_3)_2. ($$Atomic masses: Ca = 40.08, N = 14.01, O = 16.00)

Accepted Answer

$$40.08 + 2 	imes (14.01 + 3 	imes 16.00) = 164.10\ \mathrm{amu}$$

Question 12

A compound has the empirical formula CH and a molar mass of 78.11 g/mol. What is its molecular formula? (C = 12.01, H = 1.008)

Accepted Answer

$$\mathrm{C}_6\mathrm{H}_6$$

Question 13

Which of the following best describes a structural formula?

Accepted Answer

It shows the actual number and arrangement of atoms and the bonds between them.

Question 14

Which of the following is a correct statement about the octet rule?

Accepted Answer

Nonmetals in period 2 must obey the octet rule, but period 3 and below can have expanded octets when they are the central atom.

Question 15

Which of the following is the correct name for $$\mathrm{Sn(ClO}_3)_2$$?

Accepted Answer

Tin(II) chlorate

Question 16

A sample of iron(III) oxide is found to be 69.94% iron by mass. What mass of iron(III) oxide contains 58.7 g of iron?

Accepted Answer

$$\frac{58.7\ \mathrm{g\ Fe}}{0.6994} = 84.0\ \mathrm{g\ Fe_2O_3}$$

Question 17

Which of the following is a correct statement about molecular compounds?

Accepted Answer

They are composed of two or more nonmetals and exist as individual molecules.

Question 18

Which of the following is the correct name for $$\mathrm{CuSO}_4 \cdot 5\mathrm{H}_2\mathrm{O}$$?

Accepted Answer

Copper(II) sulfate pentahydrate

Chapter 4: Molecules and Compounds – Structure, Bonding, and Properties

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