chemistry test 8

In a chemical equation, the symbol (l) indicates that the substance is

liquid

Which of the following is true regarding single-displacement reactions? a. Only one product is formed. b. There is only one reagent. c. It requires oxygen. d. One element replaces another in a compound.

One element replaces another in a compound.

What are three observations that indicate a chemical change may be taking place?

They change color, form a precipitate, there is heat, production of a gas.

Which of the following indicates that a chemical equation is balanced? a. The numbers of atoms of each element are the same on both sides of the equation. b. All of the coefficients are the same. c. The numbers of molecules on each side of the equation are equal. d. The sums of the coefficients on each side of the equation are equal.

a The numbers of atoms of each element are the same on both sides

To balance a chemical equation, it is permissible to adjust the a. coefficients. b. subscripts. c. formulas of the products. d. number of products.

a. coefficients.

What type of chemical reaction is represented by the following word equation? iron oxygen → iron(II) oxide

a. synthesis

A small whole number that appears in front of a formula in a chemical equation is called a(n)

coefficient

A substance combines with oxygen, releasing a large amount of energy as heat and light, in a(n)

combustion reaction

write a word equation for 2NaI Cl2 → 2NaCl I2

sodium iodide + chlorine= sodium chloride + iodine

The general equation for a single-displacement reaction is

A+BX=AX+B

The general equation for a synthesis reaction is

A+X=AX

The general equation for a decomposition reaction is

AX=A+x

The products re-form the original reactants in a(n)

reversible reaction

following formula equations in the space provided AgNO3 + CuCl2 → AgCl + Cu(NO3)2

2AgNO3 + CuCl2 = 2AgCl + Cu(NO3)2

What is the total number of molecules that is represented by the following chemical equation? NH4NO2 → N2 2H2O

4

Metal X replaces the ions of metal Y from solution, but it cannot replace the ions of metal Z from solution. The order these metals should have in the activity series (from top to bottom) is

b. z, x, y

The law of ____________ ___ ______must be satisfied for a chemical equation to be balanced.

conservation of mass

A mixture of propane and oxygen react to form carbon dioxide and water. What type of chemical reaction is this?

d. combustion

The decomposition of a substance by an electric current is called

electrolysis

write a word equation for 2ZnS(s) 3O2(g) → 2ZnO(s) 2SO2(g)

zinc sulfide + oxygen= zinc oxide +sulfur dioxide

Which equation is not balanced? a. 2H2 O2 → 2H2O b. 4H2 2O2 → 4H2O c. H2 H2 O2 → H2O H2O d. 2H2 O2 → H2O

2H2 O2 → H2O

following formula equations in the space provided PbO2 → PbO + O2

2Pb

The general equation for a double-displacement reaction is

AX+BY=AY+BX

If calcium is listed above magnesium in the activity series, and magnesium is listed above zinc, which of the following reactions is possible?

a. Ca(s) MgCl2(aq) →

A(n) ____________orders the elements by the ease with which they undergo certain chemical reactions

activity series

To balance a chemical equation, you must

adjust the coefficients.

What symbol indicates a reversible reaction? a . ←→ b . ↑ c . → d . ←

a . ←→

In the expression 3CO2, the numbers 3 and 2 are, respectively,

a coefficient and a subscript.

calcium carbonate → calcium oxide carbon dioxide

CaCO3= CaO + CO2

What type of chemical reaction does the following chemical equation represent? 2HCl(aq) Cr(s) → H2(g) CrCl2(aq)

single-displacement

In which type of reaction do two or more compounds react to form one product? a. synthesis b. decomposition c. combustion d. single-displacement

synthesis

The coefficients in a chemical equation a. indicate the number of moles of each substance that react. b. show the number of grams of each substance that react. c. are the molar masses of the substances. d. show the valence electrons for each atom.

a. indicate the number of moles of each substance that react.

The use of a double arrow in a chemical equation indicates that the reaction a. is reversible. b. requires heat. c. is written backward. d. has not been confirmed in the laboratory.

a. is reversible.

magnesium oxygen → magnesium oxide

Mg + O2 = MgO

Which equation below violates the law of conservation of mass? a. 2H2 O2 → 2H2O b. KCl Br2 → KBr Cl2 c. 2Fe2O3 3C → 4Fe 3CO2 d. Na2CO3 2HCl → 2NaCl H2O CO2

b. KCl Br2 → KBr Cl2

If metal X is lower than metal Y in the activity series, then a. X will replace ions of Y in solution. b. Y will replace ions of X in solution. c. Y will form oxides only indirectly. d. X will react with cold water.

b. Y will replace ions of X in solution.

In a chemical equation, the symbol (aq) indicates that the substance is a. water. b. dissolved in water. c. an acid. d. insoluble.

b. dissolved in water.

The production of a slightly soluble solid compound in a double- displacement reaction results in the formation of a a. gas. b. precipitate. c. combustion reaction. d. halogen.

b. precipitate.

The activity series helps to predict a. the amount of product formed by a chemical reaction. b. whether or not a specific chemical reaction is possible. c. the coefficients needed to balance a chemical equation. d. the amount of energy needed to start a chemical reaction.

b. whether or not a specific chemical reaction is possible.

Which coefficients correctly balance the formula equation below? KClO3(s) → KCl(s) O2(g)

c. 2, 2, 3

Which of the following equations represents the balanced equation for the reaction of iron and oxygen? a. 2Fe O2 → Fe2O3 b. Fe 3O2 → Fe2O3 c. 4Fe 3O2 → 2Fe2O3 d. 3Fe 3O2 → 2Fe2O3

c. 4Fe 3O2 → 2Fe2O3

You mix solution A with solution B in a beaker. Which of the following observations does not help you prove that a chemical reaction has occurred. a. The beaker becomes warm. b. You see gas bubble out of solution. c. Solution A, solution B, and the mixture are all yellow. d. None of the above; all help prove that a chemical reaction has occurred.

c. Solution A, solution B, and the mixture are all yellow.

In a single-displacement reaction, an element in the activity series most likely can replace any element

c. below it on the list.

A(n) _____________ uses symbols and formulas to represent the names and relative amounts of reactants and products in a chemical reaction.

chemical equation

The formation of a solid product in a chemical reaction is represented by the symbol a. (aq). b. (g). c. (l). d. (s).

d (s)

From a complete and correctly written chemical equation, you can obtain the a. chemical formulas of the reactants and products. b. relative amounts of the reactants and products. c. physical states of the reactants and products. d. All of the above

d. All of the above

Which of the following is true regarding double-displacement reactions? a. Two products are formed. b. The ions of the two reactants must be exchanged. c. A precipitate may form. d. All of the above

d. All of the above

In the reaction described by the word equation sodium water → sodium hydroxide hydrogen gas a. sodium hydroxide is a product. b. sodium is a product. c. water is a reactant. d. Both (a) and (c)

d. Both (a) and (c)

Calcium carbonate, CaCO3, reacts to form calcium oxide, CaO, and carbon dioxide, CO2. What type of reaction is this?

d. decomposition

In a reaction, the ions of two compounds exchange places in aqueous solution to form two new compounds. This reaction is called a a. synthesis reaction. b. decomposition reaction. c. single-displacement reaction. d. double-displacement reaction.

d. double-displacement reaction.

The tendency for a replacement reaction to occur increases as the a. interval between any two elements in the activity series decreases. b. temperature decreases. c. valence electrons are used up. d. interval between any two elements in the activity series increases.

d. interval between any two elements in the activity series increases.

identify each chemical equation as a synthesis, decomposition, single-displacement, or double-displacement reaction. ________________________30.2H2O(l)→ 2H2(g) O2(g) ________________________31. Cl2(g) 2KBr(aq) → 2KCl(aq) Br2(l) ________________________32.CaO(s) H2O(l)→ Ca(OH)2(s) ________________________33. HCl(aq) NaOH(aq) → NaCl(aq) H2O(l)

decomposition single replacement synthesis double-displacement reaction

A(n) product is sometimes indicated by an arrow pointing upward.

gaseous

The symbol ∆→ means that the reactants are

heated

Oxides of active metals, such as CaO, react with water to form

metal hydroxides