Q: Calculate the formula mass of $$\mathrm{Al_2$(SO_4$)_3}$$ given the atomic masses: Al = 27.0, S = 32.1, O = 16.0.

$$2 \times 27.0 + 3 \times (32.1 + 4 \times 16.0) = 342.2$$

Question 1

Which of the following statements best explains why the properties of sodium chloride (table salt) are different from those of its constituent elements, sodium and chlorine?

Accepted Answer

Sodium chloride is a compound, and compounds have properties distinct from the elements that compose them.

Question 2

According to the law of constant composition, which of the following is true for all samples of pure water?

Accepted Answer

They contain hydrogen and oxygen in a fixed, definite proportion by mass.

Question 3

A 36.0 g sample of water is decomposed into hydrogen and oxygen. How many grams of oxygen are produced, given the mass ratio $$\frac{16.0\,g\,O}{2.0\,g\,H} = 8.0$$?

Accepted Answer

32.0 g

Question 4

Which of the following is the correct chemical formula for a compound containing three iron ions for every four oxide ions?

Accepted Answer

$$\mathrm{Fe_3O_4}$$

Question 5

How many oxygen atoms are present in one formula unit of $$\mathrm{Mg(NO_3$)_2}$$?

Accepted Answer

6

Question 6

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

Accepted Answer

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

Question 7

Which of the following is a molecular element?

Accepted Answer

Chlorine, Cl$$_2$$

Question 8

Which of the following compounds is classified as an ionic compound?

Accepted Answer

NaCl

Question 9

What is the correct formula for the compound formed between potassium ions and nitride ions?

Accepted Answer

$$\mathrm{K_3N}$$

Question 10

Which of the following is the correct name for the compound $$\mathrm{$$FeCl_3$$}$$?

Accepted Answer

Iron(III) chloride

Question 11

What is the correct name for $$\mathrm{Ca(C_2H_3O_2)_2}$$?

Accepted Answer

Calcium acetate

Question 12

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

Accepted Answer

$$\mathrm{Al_2$(SO_4$)_3}$$

Question 13

Which of the following is the correct name for $$\mathrm{N_2O_5}$$?

Accepted Answer

Dinitrogen pentoxide

Question 14

What is the correct name for $$\mathrm{$$HNO_2$$} (aq$$)?

Accepted Answer

Nitrous acid

Question 15

Which of the following best describes why sodium hypochlorite is effective as a bleach?

Accepted Answer

It destroys color-causing molecules and kills bacteria through oxidation.

Question 16

Calculate the formula mass of $$\mathrm{Al_2$(SO_4$)_3}$$ given the atomic masses: Al = 27.0, S = 32.1, O = 16.0.

Accepted Answer

$$2 	imes 27.0 + 3 	imes (32.1 + 4 	imes 16.0) = 342.2$$

Question 17

Which of the following is a correct statement about the naming of binary acids?

Accepted Answer

The name begins with 'hydro-', followed by the base name of the nonmetal with '-ic', and ends with 'acid'.

Question 18

Which of the following is the correct formula for phosphoric acid?

Accepted Answer

$$\mathrm{H_3PO_4}$$

Question 19

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

Accepted Answer

Molecular compounds are composed of molecules formed from nonmetals, while ionic compounds are composed of cations and anions in a lattice.

Chapter 5: Molecules and Compounds – Structured Study Notes

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