Chapter 8 Chemical Equations Solutions To Review Questions printable pdf download

C H A P T E R 8

CHEMICAL EQUATIONS

SOLUTIONS TO REVIEW QUESTIONS

1. The coefﬁcients in a balanced chemical equation represent the number of moles (or molecules or formula

units) of each of the chemical species in the reaction.

2. The physical state of a substance may be a solid, a liquid, or a gas. The symbols indicate whether a

substance is a solid, a liquid, a gas, or is in an aqueous solution. A solid is indicated by (s), a liquid by (l ),

a gas by (g) and an aqueous solution by (aq).

3. The purpose of balancing chemical equations is to conform to the Law of Conservation of Mass. Ratios of

reactants and products can then be easily determined.

4. (a)

Yes. It is necessary to conserve atoms to follow the Law of Conservation of Mass.

(b)

No. Molecules can be taken apart and rearranged to form different molecules in reactions.

(c)

Moles of molecules are not conserved (b). Moles of atoms are conserved (a).

5. These charts help to keep track of which elements are balanced in a chemical equation. The charts are

one way of keeping track of the number of atoms of each element on the reactant side of a chemical

equation and on the product side of an equation. The top row in a chart gives the number and types of

atoms on the reactant side and the bottom row gives the number and types of atoms on the product side

of a chemical equation. Using a chart may make it easier to see where coefﬁcients are needed in a reaction

and what number that coefﬁcient should be.

6. Chemical equations can only be balanced by changing the number of each substance reacted or produced.

If the subscripts are changed then the identity of the reactants and products is also changed. Equations

must be balanced using the actual reactants and products.

7. A combustion reaction is an exothermic process (usually burning) done in the presence of oxygen.

8. The activity series given in Table 8.2 shows the relative activity of certain metals and halogens. As you

move up the table starting with gold (Au) and ending with potassium (K) the activity increases. The same

is true as you move up from iodine (I

) to ﬂuorine (F

). The table is useful for predicting the products of

some reactions because an element in the series will replace any element given below it. For example,

hydrogen can replace copper, silver, mercury, or gold in a chemical reaction.

9. The major types of chemical reactions are combination reactions, decomposition reactions, single

displacement reactions, and double displacement reactions.

10. Indicators that a chemical reaction has occurred are

Formation of a precipitate

Formation of a gas

A temperature change

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Chapter 8 Chemical Equations Solutions To Review Questions