Q: Calculate the formula mass of sodium oxide (Na$$_2O). ($$Atomic masses: Na = 22.99 u, O = 16.00 u)

$$2 \times 22.99\ \mathrm{u} + 16.00\ \mathrm{u} = 61.98\ \mathrm{u}$$

Question 1

Which of the following best explains why water (H$$_2O) is $$classified as a compound, while a mixture of hydrogen and oxygen gases is not?

Accepted Answer

Water contains hydrogen and oxygen in a fixed ratio by mass, while a mixture can have any ratio.

Question 2

Which of the following statements about ionic bonds is correct?

Accepted Answer

Ionic bonds are formed by the transfer of electrons from a metal to a nonmetal.

Question 3

Given the following information, which formula represents the empirical formula for glucose (C$$_6H$_{12}O$_6$$)?

Accepted Answer

$$\mathrm{CH_2O}$$

Question 4

Which of the following is the correct name for FeCl$$_3$$?

Accepted Answer

Iron(III) chloride

Question 5

A hydrate of copper(II) sulfate has the formula CuSO$$_4$$·5H$$_2O. $$What is the correct name for this compound?

Accepted Answer

Copper(II) sulfate pentahydrate

Question 6

Which of the following best describes the difference between a molecular compound and an ionic compound?

Accepted Answer

Molecular compounds are composed of nonmetals and share electrons; ionic compounds are composed of metals and nonmetals and transfer electrons.

Question 7

Calculate the formula mass of sodium oxide (Na$$_2O). ($$Atomic masses: Na = 22.99 u, O = 16.00 u)

Accepted Answer

$$2 	imes 22.99\ \mathrm{u} + 16.00\ \mathrm{u} = 61.98\ \mathrm{u}$$

Question 8

How many moles of chlorine atoms are present in 38.5 mol of CCl$$_2F$_2$$?

Accepted Answer

$$77.0\ \mathrm{mol}$$

Question 9

Which of the following is the correct name for H$$_2SO$_3$$?

Accepted Answer

Sulfurous acid

Question 10

A sample contains 0.857 g of hydrogen and 6.86 g of oxygen. What is the empirical formula of the compound formed? (Atomic masses: H = 1.008 g/mol, O = 16.00 g/mol)

Accepted Answer

$$\mathrm{H_2O}$$

Question 11

Which of the following is the correct formula for ammonium nitrate?

Accepted Answer

$$\mathrm{NH_4NO_3}$$

Question 12

What is the mass percent of chlorine in CCl$$_2F$_2$$? (Atomic masses: C = 12.01 g/mol, Cl = 35.45 g/mol, F = 19.00 g/mol)

Accepted Answer

$$58.64\%$$

Question 13

Which of the following is a correct representation of the mole concept for CO$$_2$$?

Accepted Answer

$$1\ \mathrm{mol\ CO_2$} = 44.01\ \mathrm{g\ CO_2$} = 6.022 	imes 10$$^{23}$$\ \mathrm{molecules\ CO_2$}$$

Question 14

Which of the following is the correct name for NaNO$$_2$$?

Accepted Answer

Sodium nitrite

Question 15

Which of the following best describes a hydrate?

Accepted Answer

An ionic compound that contains a specific number of water molecules associated with each formula unit.

Question 16

Which of the following is the correct formula for calcium sulfate hemihydrate?

Accepted Answer

$$\mathrm{$$CaSO_4$$ \cdot \frac{1}{2}H_2O}$$

Question 17

Which of the following is the correct name for N$$_2O$$?

Accepted Answer

Dinitrogen monoxide

Question 18

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

Accepted Answer

Compounds have a fixed, definite proportion of elements by mass.

Question 19

Which of the following is the correct name for HCl(aq)?

Accepted Answer

Hydrochloric acid

Question 20

A colorless liquid has a composition of 84.1% carbon and 15.9% hydrogen by mass. If its molar mass is 114.2 g/mol, what is its molecular formula?

Accepted Answer

$$\mathrm{C_8H_{18}}$$

Molecules, Compounds, and Nomenclature: Study Guide

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