Chapter 8: Chemical Equations and Reactions

List observations that suggest that a chemical reaction has taken place.

1. Evolution of energy as heat and light 2. Production of a gas 3. Formation of a precipitate 4. Color change

List three requirements for a correctly written chemical equation.

1. The equation must represent known facts. 2. The equation must contain the correct formulas for the reactants and products. 3. The law of conservation of mass must be satisfied.

An active metal and a halogen react to form a(n) (A) salt. (B) hydroxide. (C) acid. (D) oxide.

A

The decomposition of a substance by an electric current is called (A) electrolysis. (B) conduction. (C) ionization. (D) transformation.

A

The reaction 2Mg(s) + O2(g) 2MgO(s) is a (A) synthesis reaction. (B) decomposition reaction. (C) single-replacement reaction. (D) double-replacement reaction.

A

The reaction Pb(NO3)2(aq) + 2KI(aq) PbI2(s) + 2KNO3(aq) is a (A) double-replacement reaction. (B) synthesis reaction. (C) decomposition reaction. (D) combustion reaction.

A

To balance a chemical equation, it may be necessary to adjust the (A) coefficients. (B) subscripts. (C) formulas of the products. (D) number of products.

A

A chemical equation is balanced when the (A) coefficients of the reactants equal the coefficients of the products. (B) same number of each kind of atom appears in the reactants and in the products. (C) products and reactants are the same chemicals. (D) subscripts of the reactants equal the subscripts of the products.

B

An element in the activity series can replace any element (A) in the periodic table. (B) below it on the list. (C) above it on the list. (D) in its group.

B

When heated, a metal carbonate decomposes into a metal oxide and (A) carbon. (B) carbon dioxide. (C) oxygen. (D) hydrogen.

B

Knowledge about what products are produced in a chemical reaction is obtained by (A) inspecting the chemical equation. (B) balancing the chemical equation. (C) laboratory analysis. (D) writing a word equation.

C

The reaction Mg(s) + 2HCl(aq) H2(g) + MgCl2(aq) is a (A) composition reaction. (B) decomposition reaction. (C) single-replacement reaction. (D) double-replacement reaction.

C

If chlorine gas is produced by halogen replacement, the other halogen in the reaction must be (A) bromine. (B) iodine. (C) astatine. (D) fluorine.

D

Predict what happens when lead is added to nitric acid. (A) No reaction occurs. (B) Oxygen is released. (C) Lead oxide forms. (D) Hydrogen is released.

D

The reaction 2HgO(s) 2Hg(l) + O2(g) is a(n) (A) single-replacement reaction. (B) synthesis reaction. (C) ionic reaction. (D) decomposition reaction.

D

When the equation Fe3O4 + Al Al2O3 + Fe is correctly balanced, what is the coefficient of Fe? (A) 3 (B) 4 (C) 6 (D) 9

D

List five types of decomposition reactions.

DECOMPOSITION: 1. decomposition of binary compounds 2. metal carbonates 3. metal hydroxides 4. metal chlorates 5. acids

List three types of double-replacement reactions.

DOUBLE: 1. formation of a precipitate 2. formation of a gas 3. formation of water

List four types of single-replacement reactions.

SINGLE: 1. replacement of a metal in a compound by another metal 2. replacement of hydrogen in water by a metal 3. replacement of hydrogen in an acid by a metal 4. replacement of halogens

List three types of synthesis reactions.

SYNTHESIS: 1. reactions of elements with oxygen and sulfur 2. reactions of metals with halogens (3) synthesis reactions with oxides 3. synthesis reactions with oxides

Explain the significance of an activity series.

The more active the element, the higher up on the activity list they are. Elements lower than others on the activity series cannot replace other elements in a single-replacement reaction. They are used to predict if certain reactions will occur.

Write a word equation and a formula equation for a given chemical reaction. solid sodium oxide is added to water at room temperature and forms sodium hydroxide (dissolved in the water)

The word equation must show the reactants, sodium oxide and water, to the left of the arrow. The product, sodium hydroxide, must appear to the right of the arrow. sodium oxide + water ⎯→ sodium hydroxide Na2O(s) + H2O(l) ⎯→ 2NaOH(aq)

Definition: a reaction in which a substance combines with oxygen, releasing a large amount of energy in the form of light and heat

combustion reaction

Definition: a reaction in which a single compound produces two or more simpler substances

decomposition reaction

Definition: a reaction in which one element replaces a similar element in a compound

displacement reaction

Definition: a reaction in which the ions of two compounds exchange places in an aqueous solution to form two new compounds

double-replacement reaction

Definition: the decomposition of a substance by an electric current

electrolysis

Definition: a solid that is produced as a result of a chemical reaction in solution and that separates from the solution

precipitate

Definition: a chemical reaction in which the products re-form the original reactants

reversible reaction

Definition: a reaction in which one element replaces a similar element in a compound

single-replacement reaction

Definition: a reaction in which two or more substances combine to form a new compound

synthesis reaction