Chapter 7

What is the difference between a physical change and a chemical change? List some examples of each.

What is the difference between a physical property and a chemical property?

Why must chemical equations be balanced?

What is reaction stoichiometry? What is the significance of the coefficients in a balanced chemical equation?

What is a combustion reaction? Why are they important? Give an example.

Write a general equation for the reaction of an alkali metal with: a. a halogen b. water

Write a general equation for the reaction of a halogen with: a. a metal b. hydrogen c. another halogen

Classify each change as physical or chemical. a. Natural gas burns in a stove. b. The liquid propane in a gas grill evaporates because the valve was left open. c. The liquid propane in a gas grill burns in a flame. d. A bicycle frame rusts on repeated exposure to air and water.

Classify each change as physical or chemical. a. Sugar burns when heated on a skillet. b. Sugar dissolves in water. c. A platinum ring becomes dull because of continued abrasion. d. A silver surface becomes tarnished after exposure to air for a long period of time.

Classify each of the listed properties of isopropyl alcohol (also known as rubbing alcohol) as physical or chemical. a. colorless b. flammable c. liquid at room temperature d. density = 0.79 g>mL e. mixes with water

Classify each of the listed properties of ozone (a pollutant in the lower atmosphere, but part of a protective shield against UV light in the upper atmosphere) as physical or chemical. a. bluish color b. pungent odor c. very reactive d. decomposes on exposure to ultraviolet light e. gas at room temperature

Classify each property as physical or chemical. a. the tendency of ethyl alcohol to burn b. the shine of silver c. the odor of paint thinner d. the flammability of propane gas

Classify each property as physical or chemical. a. the boiling point of ethyl alcohol b. the temperature at which dry ice evaporates c. the tendency of iron to rust d. the color of gold

Sulfuric acid (H2SO4) is a component of acid rain that forms when gaseous sulfur dioxide pollutant reacts with gaseous oxygen and liquid water to form aqueous sulfuric acid. Write a balanced chemical equation for this reaction. (Note: This is a simplified representation of this reaction.)

Nitric acid (HNO3) is a component of acid rain that forms when gaseous nitrogen dioxide pollutant reacts with gaseous oxygen and liquid water to form aqueous nitric acid. Write a balanced chemical equation for this reaction. (Note: This is a simplified representation of this reaction.)

In a popular classroom demonstration, solid sodium is added to liquid water and reacts to produce hydrogen gas and aqueous sodium hydroxide. Write a balanced chemical equation for this reaction.

When iron rusts, solid iron reacts with gaseous oxygen to form solid iron(III) oxide. Write a balanced chemical equation for this reaction.

Write a balanced chemical equation for the fermentation of sucrose (C12H22O11) by yeasts in which the aqueous sugar reacts with liquid water to form aqueous ethyl alcohol (C2H5OH) and carbon dioxide gas.

Write a balanced equation for the photosynthesis reaction in which gaseous carbon dioxide and liquid water react in the presence of chlorophyll to produce aqueous glucose (C6H12O6) and oxygen gas.

Write a balanced chemical equation for each reaction. a. Solid lead(II) sulfide reacts with aqueous hydrobromic acid (HBr) to form solid lead(II) bromide and dihydrogen monosulfide gas. b. Gaseous carbon monoxide reacts with hydrogen gas to form gaseous methane (CH4) and liquid water. c. Aqueous hydrochloric acid (HCl) reacts with solid manganese(IV) oxide to form aqueous manganese(II) chloride, liquid water, and chlorine gas. d. Liquid pentane (C5H12) reacts with gaseous oxygen to form gaseous carbon dioxide and liquid water.

Write a balanced chemical equation for each reaction. a. Solid copper reacts with solid sulfur to form solid copper(I) sulfide. b. Solid iron(III) oxide reacts with hydrogen gas to form solid iron and liquid water. c. Sulfur dioxide gas reacts with oxygen gas to form sulfur trioxide gas. d. Gaseous ammonia (NH3) reacts with gaseous oxygen to form gaseous nitrogen monoxide and gaseous water.

Write a balanced chemical equation for the reaction of aqueous sodium carbonate with aqueous copper(II) chloride to form solid copper(II) carbonate and aqueous sodium chloride.

Write a balanced chemical equation for the reaction of aqueous potassium hydroxide with aqueous iron(III) chloride to form solid iron(III) hydroxide and aqueous potassium chloride.

Consider the unbalanced equation for the combustion of hexane: C6H14(g) + O2(g)-CO2(g) + H2O(g) Balance the equation and determine how many moles of O2 are required to react completely with 7.2 moles C6H14.

Consider the unbalanced equation for the neutralization of acetic acid: HC2H3O2(aq) + Ba(OH)2(aq)-H2O(l ) + Ba(C2H3O2)2(aq) Balance the equation and determine how many moles of Ba(OH)2 are required to completely neutralize 0.461 mole of HC2H3O2.

Consider the balanced equation: SiO2(s) + 3 C(s)-SiC(s) + 2 CO(g) Complete the following table showing the appropriate number of moles of reactants and products. If the number of moles of a reactant is provided, fill in the required amount of the other reactant, as well as the moles of each product that forms. If the number of moles of a product is provided, fill in the required amount of each reactant to make that amount of product, as well as the amount of the other product that is made.

Consider the balanced equation: 2 N2H4(g) + N2O4(g)-3 N2(g) + 4 H2O(g) Complete the following table showing the appropriate number of moles of reactants and products. If the number of moles of a reactant is provided, fill in the required amount of the other reactant, as well as the moles of each product that forms. If the number of moles of a product is provided, fill in the required amount of each reactant to make that amount of product, as well as the amount of the other product that is made.

Sulfuric acid (H2SO4) dissolves aluminum metal according to the reaction: 2 Al(s) + 3 H2SO4(aq)-Al2(SO4)3(aq) + 3 H2(g) Suppose you want to dissolve an aluminum block with a mass of 15.2 g. What minimum mass of H2SO4 (in g) do you need? What mass of H2 gas (in g) can the complete reaction of the aluminum block produce?

For each of the reactions, calculate the mass (in grams) of the product that forms when 3.67 g of the underlined reactant completely reacts. Assume that there is more than enough of the other reactant. a. Ba(s) + Cl2(g)-BaCl2(s) b. CaO(s) + CO2(g)-CaCO3(s) c. 2 Mg(s) + O2(g)-2 MgO(s) d. 4 Al(s) + 3 O2(g)-2 Al2O3(s)

For each of the reactions, calculate the mass (in grams) of the product that forms when 15.39 g of the underlined reactant completely reacts. Assume that there is more than enough of the other reactant. a. 2 K(s) + Cl2(g)-2 KCl(s) b. 2 K(s) + Br2(l)-2 KBr(s) c. 4 Cr(s) + 3 O2(g)-2 Cr2O3(s) d. 2 Sr(s) + O2(g)-2 SrO(s)

For the following reaction, determine the limiting reactant for each of the initial amounts of reactants. 2 Na(s) + Br2(g)-2 NaBr(s) a. 2 mol Na, 2 mol Br2 b. 1.8 mol Na, 1.4 mol Br2 c. 2.5 mol Na, 1 mol Br2 d. 12.6 mol Na, 6.9 mol Br2

Find the limiting reactant for each initial amount of reactants. 4 Al(s) + 3 O2(g)-2 Al2O3(s) a. 1 mol Al, 1 mol O2 b. 4 mol Al, 2.6 mol O2 c. 16 mol Al, 13 mol O2 d. 7.4 mol Al, 6.5 mol O2

Calculate the theoretical yield of the product (in moles) for each initial amount of reactants. Ti(s) + 2 Cl2(g)-TiCl4(s) a. 4 mol Ti, 4 mol Cl2 b. 7 mol Ti, 17 mol Cl2 c. 12.4 mol Ti, 18.8 mol Cl2

Calculate the theoretical yield of product (in moles) for each initial amount of reactants. 2 Mn(s) + 2 O2(g)-2 MnO2(s) a. 3 mol Mn, 3 mol O2 b. 4 mol Mn, 7 mol O2 c. 27.5 mol Mn, 43.8 mol O2

Zinc sulfide reacts with oxygen according to the reaction: 2 ZnS(s) + 3 O2(g)-2 ZnO(s) + 2 SO2(g) A reaction mixture initially contains 4.2 mol ZnS and 6.8 mol O2. Once the reaction has occurred as completely as possible, what amount (in moles) of the excess reactant remains?

Iron(II) sulfide reacts with hydrochloric acid according to the reaction: FeS(s) + 2 HCl(aq)-FeCl2(s) + H2S(g) A reaction mixture initially contains 0.223 mol FeS and 0.652 mol HCl. Once the reaction has occurred as completely as possible, what amount (in moles) of the excess reactant is left?

For the reaction shown, calculate the theoretical yield of product (in grams) for each initial amount of reactants. 2 Al(s) + 3 Cl2(g)-2 AlCl3(s) a. 2.0 g Al, 2.0 g Cl2 b. 7.5 g Al, 24.8 g Cl2 c. 0.235 g Al, 1.15 g Cl2

For the reaction shown, calculate the theoretical yield of the product (in grams) for each initial amount of reactants. Ti(s) + 2 F2(g)-TiF4(s) a. 5.0 g Ti, 5.0 g F2 b. 2.4 g Ti, 1.6 g F2 c. 0.233 g Ti, 0.288 g F2

Iron(III) oxide reacts with carbon monoxide according to the equation: Fe2O3(s) + 3 CO(g)-2 Fe(s) + 3 CO2(g) A reaction mixture initially contains 22.55 g Fe2O3 and 14.78 g CO. Once the reaction has occurred as completely as possible, what mass (in g) of the excess reactant remains?

Elemental phosphorus reacts with chlorine gas according to the equation: P4(s) + 6 Cl2(g)-4 PCl3(l) A reaction mixture initially contains 45.69 g P4 and 131.3 g Cl2. Once the reaction has occurred as completely as possible, what mass (in g) of the excess reactant remains?

Magnesium oxide can be made by heating magnesium metal in the presence of oxygen. The balanced equation for the reaction is: 2 Mg(s) + O2(g)-2 MgO(s) When 10.1 g of Mg reacts with 10.5 g O2, 11.9 g MgO forms. Determine the limiting reactant, theoretical yield, and percent yield for the reaction.

Complete and balance each combustion reaction equation. a. S(s) + O2(g) b. C3H6(g) + O2(g) c. Ca(s) + O2(g) d. C5H12S(l) + O2(g)

Complete and balance each combustion reaction equation: a. C4H6(g) + O2(g) b. C(s) + O2(g) c. CS2(s) + O2(g) d. C3H8O(l) + O2(g)

Write a balanced chemical equation for the reaction of solid strontium with iodine gas.

Write a balanced chemical equation for the reaction of solid lithium with liquid water.

Write a balanced chemical equation for the reaction of solid potassium with liquid water.

Write a balanced equation for the reaction of hydrogen gas with bromine gas.

Write a balanced equation for the reaction of chlorine gas with fluorine gas.

The combustion of gasoline produces carbon dioxide and water. Assume gasoline to be pure octane (C8H18) and calculate the mass (in kg) of carbon dioxide that is added to the atmosphere per 1.0 kg of octane burned. (Hint: Begin by writing a balanced equation for the combustion reaction.)

Many home barbeques are fueled with propane gas (C3H8). What mass of carbon dioxide (in kg) forms upon the complete combustion of 18.9 L of propane (approximate contents of one 5-gallon tank)? Assume that the density of the liquid propane in the tank is 0.621 g>mL. (Hint: Begin by writing a balanced equation for the combustion reaction.)