$$40.08 + 2 \times (16.00 + 1.01) = 74.10$$

$$0.40 \times 13 \times 6.022 \times 10$$^{23}$$

$$\frac{2 \times 16.00}{12.01 + 2 \times 16.00} \times 100 = 72.7\%$$

$$50.0 \times \frac{32.00}{44.01} = 36.4 g$$

Question 1

Which statement best describes what a molecular formula tells you about a compound?

Accepted Answer

It gives the relative numbers and types of atoms in a molecule.

Question 2

Which of the following is an example of a molecular element?

Accepted Answer

O$$_2$$

Question 3

What is the main difference between an ionic compound and a molecular compound?

Accepted Answer

Ionic compounds consist of cations and anions held together by electrostatic forces, while molecular compounds consist of neutral molecules.

Question 4

Which formula represents the empirical formula for glucose?

Accepted Answer

CH$$_2O$$

Question 5

A compound is formed when:

Accepted Answer

Two or more elements combine to form a substance with properties different from its components.

Question 6

Which of the following best describes a cation?

Accepted Answer

An atom that loses one or more electrons.

Question 7

Calculate the formula mass of calcium hydroxide, Ca(OH)$$_2. ($$Atomic masses: Ca = 40.08, O = 16.00, H = 1.01)

Accepted Answer

$$40.08 + 2 	imes (16.00 + 1.01) = 74.10$$

Question 8

How many atoms of carbon are present in 0.40 mole of procaine, C$$_{13}H$_{20}N$_2O$_2$$?

Accepted Answer

$$0.40 	imes 13 	imes 6.022 	imes 10$$^{23}$$

Question 9

What is the percent by mass of oxygen in CO$$_2$$? (Atomic masses: C = 12.01, O = 16.00)

Accepted Answer

$$\frac{2 	imes 16.00}{12.01 + 2 	imes 16.00} 	imes 100 = 72.7\%$$

Question 10

Which of the following is a correct statement about formula mass and molar mass?

Accepted Answer

Formula mass and molar mass are synonymous; both refer to the mass of one mole of a substance.

Question 11

Which of the following best describes an empirical formula?

Accepted Answer

It gives the simplest whole-number ratio of atoms in a compound.

Question 12

A sample contains 50.0 g of CO$$_2. $$How many grams of oxygen are present in the sample? (Atomic masses: C = 12.01, O = 16.00)

Accepted Answer

$$50.0 	imes \frac{32.00}{44.01} = 36.4 g$$

Question 13

Which of the following is NOT true about ionic compounds?

Accepted Answer

They exist as discrete molecules.

Question 14

What is the percent by mass of lead in lead(II) chromate, PbCrO$$_4$$? (Atomic masses: Pb = 207.2, Cr = 52.00, O = 16.00)

Accepted Answer

$$\frac{207.2}{207.2 + 52.00 + 4 	imes 16.00} 	imes 100 = 62.8\%$$

Question 15

Which of the following is a correct statement about elements and compounds?

Accepted Answer

Compounds are formed when two or more elements combine to form a substance with properties different from its components.

Question 16

Which of the following is a correct formula for ammonium chloride?

Accepted Answer

NH$$_4Cl$$

Question 17

If a molecule contains 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms, what is its molecular formula?

Accepted Answer

C$$_6H$_{12}O$_6$$

Question 18

Which of the following is a property of molecular compounds?

Accepted Answer

They consist of neutral molecules.

Question 19

Which of the following is the correct formula for the number of moles in a given mass of a compound?

Accepted Answer

$$	ext{moles} = \frac{	ext{mass (g)}}{	ext{molar mass (g/mol)}}$$

Chemical Formulas, Compounds, and Nomenclature: Study Notes for General Chemistry I

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