Chapter 7: Chemical Reactions

When the equation, ___O2 + ___C 8H 18 → ___CO2 + ___H2O is balanced, the coefficient of O2 is: a) 25 b) 4 c) 50 d) 13 e) none of the above

a) 25

When a solution of MgCl2 and one of AgNO3 are mixed, the net ionic equation is: a) Cl-(aq) + Ag+(aq) → AgCl(s) b) Mg2+(aq) + 2Cl-(aq) + 2Ag+(aq) + 2NO3- (aq) → Mg (NO3)2 (aq) + 2 AgCl(s) c) Mg2+(aq) + 2Cl-(aq) + 2Ag+(aq) + 2NO3- (aq) → Mg2+(aq) + 2NO3-aq) + 2AgCl(s) d) Mg2+(aq) + 2NO3-(aq) →Mg (NO3)2(aq) e) none of the above

a) Cl-(aq) + Ag+(aq) → AgCl(s)

Considering the following precipitation reaction: Pb(NO3)2(aq) + 2KI(aq) → PbI2(s) + 2KNO3(aq) Which ion(s) would NOT be spectator ions? a) Pb2+, I- b) K+, I- c) Pb2+, NO3 - d) NO3 -, Pb2+ e) All the above ions are in the net ionic equation.

a) Pb2+, I-

Which of the following compounds is INSOLUBLE? a) aluminum sulfide b) lithium carbonate c) magnesium bromide d) potassium acetate e) none of the above

a) aluminum sulfide

Before a chemical equation can be written, one must know: a) the symbols and formulas of all reactants and products. b) the atomic mass of all the elements involved. c) the molar mass of all the compounds. d) the number of moles of all reactants and products. e) none of the above.

a) the symbols and formulas of all reactants and products.

In writing the chemical equation for a precipitation reaction, what abbreviation of the physical state must appear with one of the products? a) (g) b) (s) c) (w) d) (l) e) none of the above

b) (s)

When water is heated, bubbles form in the water. Is this evidence of a chemical reaction? Why? a) No, the formation of gas bubbles is a secondary chemical reaction which is ignored. b) No, boiling water is a physical change. c) Yes, the formation of a gas is proof a new compound has been made. d) Yes, the formation of a gas is evidence of a chemical reaction. e) none of the above

b) No, boiling water is a physical change.

What would be the formula of the precipitate that forms when Pb(NO3)2 (aq) and K2SO4 (aq) are mixed? a) H2O b) PbSO4 c) K(NO3)2 d) PbK2 e) none of the above

b) PbSO4

Several grams of sodium chloride are stirred into a glass of water and are no longer visible to the eye. Which of the following statements is FALSE? a) No precipitate has formed. b) Sodium chloride is insoluble in water. c) The sodium chloride solid has dissociated into its component ions. d) An aqueous solution has been prepared.

b) Sodium chloride is insoluble in water.

A reaction which forms a gaseous product is an example of a(n): a) precipitation reaction b) gas evolution reaction c) combustion reaction d) oxidation-reduction reaction e) none of the above

b) gas evolution reaction

What are the coefficients for the following reaction when it is properly balanced? ___nitrogen monoxide + ___carbon monoxide → ___nitrogen +___carbon dioxide a) 1, 1, 2, 2 b) 2, 2, 2, 1 c) 2, 2, 1, 2 d) 2, 1, 1, 2 e) none of the above

c) 2, 2, 1, 2

When the equation, ___N2 + ___H2 → ___NH3 is balanced, the coefficient of hydrogen is: a) 1 b) 2 c) 3 d) 4 e) none of the above

c) 3

Considering the following precipitation reaction: Pb(NO3)2(aq) + 2KI(aq) → PbI2(s) + 2KNO3(aq) Which compound would not form ions in the complete ionic equation? a) KNO3 b) Pb(NO3)2 c) PbI2 d) KI e) All compounds form ions in the complete ionic equation.

c) PbI2

When solid NaCl is stirred into water, which of the following is NOT true? a) The solution will taste salty. b) Individual sodium and chloride ions are present. c) The NaCl will fail to dissociate. d)The solution will conduct electricity. e) none of the above

c) The NaCl will fail to dissociate.

Which of the following statements about balancing reactions is FALSE? a) Subscripts are multiplied by the coefficients to determine the number of atoms in a compound. b) Coefficients are added to compounds to ensure both sides of the reaction have equal numbers of each atom. c) When coefficients are added the type of compounds is changed in the chemical reaction. d) If there is no coefficient or subscript, a one is implied. e) All of the above statements are true.

c) When coefficients are added the type of compounds is changed in the chemical reaction.

A reaction in which a substance reacts with oxygen, emitting heat and forming oxygen-containing compounds is an example of a(n): a) gas evolution reaction. b) acid-base reaction. c) combustion reaction. d) precipitation reaction. e) none of the above

c) combustion reaction

Which of the following compounds is SOLUBLE? a) strontium carbonate b) calcium carbonate c) potassium carbonate d) copper carbonate e) none of the above

c) potassium carbonate

A reaction which forms a solid product is an example of a(n): a) gas evolution reaction. b) combustion reaction. c) precipitation reaction. d) oxidation-reduction reaction. e) none of the above

c) precipitation reaction

Considering the following precipitation reaction: Pb(NO3)2(aq) + 2KI(aq) → PbI2(s) + 2KNO3(aq) What is the correct net ionic equation? a) Pb2+ + 2NO3- + 2K+ + 2I- → PbI2(s) + 2K+ + 2NO3- b) Pb2+ + I2- → PbI2(s) c) 2NO3- + 2K+ → 2KNO3 d) Pb2+ + 2I- → PbI2(s) e) none of the above

d) Pb2+ + 2I- → PbI2(s)

Which of the following compounds is INSOLUBLE? a) magnesium sulfate b) magnesium iodide c) magnesium nitrate d) magnesium phosphate e) none of the above

d) magnesium phosphate

An aqueous solution is: a) any liquid with another compound dissolved in it. b) an ionic compound with water dissolved in it. c) water with another compound dissolved in it. d) water with a molecular compound dissolved in it. e) none of the above

d) water with another compound dissolved in it.

Which of the following is NOT evidence that a chemical reaction has occurred? a) emission of light when chemicals are contact with each other b) solid formation when chemicals are contacted with each other c) gas formation when chemicals are contacted with each other d) color change when chemicals are contacted with each other e) All of the above are evidence of a chemical reaction.

e) All of the above are evidence of a chemical reaction.

Which of the following statements about writing molecular, complete and net ionic equations is FALSE? a) A complete ionic equation is a chemical equation showing all of the species as they are actually present in solution. b) A molecular equation is a chemical equation showing the complete, neutral formulas for every compound in a reaction. c) A net ionic equation is an equation showing only the species that actually participate in the reaction. d) A spectator ion remains unchanged in the reaction and appears on both sides of the equation. e) All of the statements are true.

e) All of the statements are true.