Chapter 8.1, 8.2 Questions

What four guidelines are useful in balancing equations?

1. Identify the names of the reactants and products (create a word equation) 2. Write the formula equation 3. Balance equation for law of conservation of matter 4. Check work and see if equation is balanced

List the three requirements for a correctly written chemical formula.

1. It must represent the known facts 2. Contain the correct formula for the reactants and products 3. Satisfy the law of conservation of mass

Define and give general equations for the five basic types of chemical reactions introduced in Chapter 8.

1. Synthesis reaction: A synthesis reaction occurs when two or more simple compounds combine to form a more complicated one. ex: A + B --> AB 2. Decomposition reaction: A decomposition reaction occurs when a complex molecule breaks down to make simpler ones. ex: AB --> A + B 3. Single-displacement reaction: A single displacement reaction occurs when one element trades places with another element in a compound. ex: A + BC --> AC + B 4. Double-displacement reaction: A double displacement reaction occurs when the anions and cations of two different molecules switch places, forming two entirely different compounds. ex: AB + CD --> AD + CB 5. Combustion reaction: A combustion reaction occurs when oxygen combines with another substance, releasing a large amount of energy in the form of light and heat. ex: CxHy + O₂ --> CO₂ + H₂O* ... always produces CO₂ and H₂O *(general formula however some vary such as production of water vapor i.e. 2H₂ + O₂ --> 2H₂O)

What quantitative information is revealed by a chemical equation?

1. The coefficients of a chemical reaction indicate relative, not absolute, amounts of reactants and products. 2. The relative masses of the reactants and products of a chemical reaction can be determined from the reaction's coefficients. 3. The reverse reaction for a chemical equation has the same relative amounts of substances as the forward reaction.

List four observations that indicate that a chemical reaction may be taking place.

1. The evolution of energy 2. The production of a gas 3. The formation of a precipitate 4. Color change

Give an example of a word equation a formula equation and a chemical equation.

1. Word equation: hydrogen plus oxygen yields water 2. Formula equation: H₂ + O2 -> H2O 3. Chemical equation: 2H₂ + O2 -> 2H₂O

The reaction of Vanadium (II) oxide with Iron (III) oxide results in the formation of Vanadium (V) oxide and Iron (II) oxide. Write the balanced Equation

2VO + 3Fe₂O₃ --> V2O₅ + 6FeO

How are most decomposition reactions initiated?

A source of energy such as electrolysis or heat

In what environment do many single-displacement reactions commonly occur?

Aqueous solutions

List five types of chemical reactions

Decomposition reaction, synthesis reaction, single-displacement reaction, double-displacement reaction and combustion reaction

A substance is decomposed by an electric current. What is the name of this type of reaction?

Electrolysis

What is meant by the term "coefficient" in relation to a chemical equation?

It is the number that appears in front of a formula in a chemical equation

How do single displacement reactions compare with synthesis and decomposition reactions in terms of the amount of energy involved?

Single-displacement reactions require less energy

How does the presence of a coefficient affect the number of atoms of each type in the formula that the coefficient precedes?

The number of atoms of each type in the formula is multiplied by the coefficient

Write the word, formula, chemical equations for the reaction between hydrogen sulfide gas and oxygen gas that produces sulfur dioxide gas and water vapor.

Word Equation: Hydrogen Sulfide + oxygen --> Sulfur Dioxide + Water Vapor Formula Equation: H₂S(g) + O₂ (g)--> SO₂(g) + H2O (g) Chemical Equation: 2H₂S(g) + 3O₂ (g)--> 2SO₂(g) + 2H₂O (g)

What limitations are associated with the use of both word and formula equations?

Word and formula equations have only qualitative meaning; they do not express the relative quantities of a reaction's reactants or products

Write word and formula equations for the reaction in which aqueous solutions of sulfuric acid and sodium hydroxide reacts to form aqueous sodium sulfate and water

a) Word equation: Sulfuric acid + sodium hydroxide --> Sodium sulfate + water b) Formula equation: H₂SO₄ (aq) + NaOH (aq) --> Na₂SO₄ (aq) + H₂O

The difference between word equations, formula equations, and chemical equation

a) Word equation: qualitative; uses words to represent the reactants and products in a chemical reaction b) Formula equation: also qualitative; it uses chemical symbols or formulas, but does not reveal the rations of the reactants and products. c) Chemical equation: a balanced formula

For each of the following reactions, write the missing product(s) and then balance the resulting equation. Identify each reaction by type: a) Br₂ + KI --> _________ b) 2NaClO₃ --"triangle"--> _________ c) 2C₇H₁₄ + 21O₂ --> _________ d) CuCl₂ + Na₂S --> _________

a. 2KBr + I2 (single replacement) b. 2 NaCl + 3 O2 (decomposition) c. 14 CO2 + 14 H2O (combustion) d. 2 NaCl + CuS (precipitation)

In an experiment, an iron sample is oxidized to iron (III) oxide by oxygen, which is generated in the thermal decomposition of potassium chlorate. Write the two chemical reactions in the correct sequence.

a. 2KClO₃ --heat --> 2KCl + 3O₃ b. 4Fe + 3O₃ --> 2Fe2O₃

For each of the following reaction, identify the missing reactant(s) or product(s) and then balance the resulting equation. Note that each empty slot may require one or more substances. a. Synthesis: _________ --> Li₂O b. Decomposition: Mg(CIO₃)₂ --> _________ c. Double-displacement: HNO₃ + Ca(OH)₂ --> ________ d. Combustion: C₅H₁₂ + O₂ --> _________

a. 4Li + O₂ b. MgCl₂ + 3O₂ c. Ca(NO₃)₂ + 2H₂O d. 5CO₂ + 6H₂O

How many atoms of each type are represented in each of the following? a. 3N₂ b. 2H₂O c. 4HNO₃ d. 2Ca(OH)₂ e. 3Ba(ClO₃)₂ f. 5Fe(NO₃)₂ g. 4Mg₃(PO₄)₂ h. 2(NH₄)₂SO₄ i. 6Al₂(SeO₄)₃ j. 4C₃H₈

a. 6N b. 4H, 2O c. 4H, 4N, 12O d. 2Ca, 4O, 4H e. 3Ba, 6Cl, 18O f. 5Fe, 10N, 30O g. 12Mg, 8P, 32O h. 4N, 16H, 2S, 8O i. 12Al, 18Se, 72O j. 12C, 32H

Define the following terms: a. Aqueous solution b. Catalyst c. Reversible reaction

a. Aqueous solution: solution in water b. Catalyst: a substance that accelerates a chemical reaction but can be recovered unchanged c. Reversible reaction: a chemical reaction in which the products reform the original reactants

Write formulas for each of the following compounds: a. potassium hydroxide b. Calcium nitrate c. Sodium bicarbonate d. Carbon tetrachloride e. Magnesium bromide

a. K₂O b. Ca(NO₃)₂ c. NaHCO₃ d. CCl₄ e. MgBr₂

Translate the following chemical equations into sentences a. 2K (s) + 2H₂O (l) --> 2KOH (aq) + H₂ (g) b. 2Fe (s) + 3Cl₂ (g) --> 2FeCl (s)

a. Solid Potassium metal reacts with liquid water to form aqueous Potassium hydroxide and hydrogen gas b. Solid iron metal reacts with chlorine gas to produce solid iron (III) chloride

Classify each of the following reactions as synthesis, decomposition, single-displacement, double-displacement or combustion: a. N₂(g) + 3H₂(g) --> 2NH₃(g) b) 2Li(s) + 2H₂O(l) --> 2LioH(aq) + H₂(g) c) 2NaNO₃(s) --> 2NaNO₂(s) + O₂(g) d) 2C₆H₁₄(l) + 1902(g) --> 12CO₂(g) + 14H₂O(l)

a. Synthesis b. Single-displacement c. Decomposition d. Combustion