Chapter 5 Section Reviews Name:

Section 1: The Nature of Chemical Reactions

_____1.Which of these is not a sign of a chemical reaction?

a.A gas is given off. c. Heat is released.

b.The material dissolves. d. A color change occurs.

_____2.The substance that is formed in a chemical reaction is called the

a.polymer. c. radical.

b.reactant. d. product.

_____3.Which of the following stores chemical energy?

a.the temperature of a substance c.the bonds of a molecule

b.the density of a substance d. the nucleus of an atom

_____4.Which of the following occurs in an endothermic reaction but not in an exothermic reaction?

a.Chemical bonds are broken. c. Molecules are formed.

b.Energy is absorbed. d. Atoms are rearranged.

_____5.A type of reaction that produces an increase in temperature is

a.endothermic. c. covalent.

b.exothermic. d. nonpolar.

_____6.An example of an endothermic reaction is

a.boiling water. c. burning gasoline.

b.an exploding firecracker. d. photosynthesis by a plant.

_____7.A reaction in which the products contain more chemical energy than the reactants is

a.exothermic. c. endothermic.

b.electrical. d. exergonic.

_____8.Which of these represents the release of chemical energy?

a.pouring gasoline into a tank c. a toy car running down a ramp

b.burning charcoal in a grill d. warming food in a microwave

_____9.Which of the following are the products and reactants of a chemical reaction most likely to have in common?

a.atoms c. physical properties

b.molecules d. chemical properties

_____10.Which of the following occurs when gasoline is burned?

a.New elements are formed. c. New molecules are formed.

b.New atoms are formed. d. All of the above

Section: Reaction Types

_____11. The decomposition of water can be brought about by

a.combustion. c. synthesis reactions.

b.electrolysis. d. oxidation.

_____12. In an oxidation-reduction reaction,

a.both substances gain electrons.

b.both substances lose electrons.

c.one substance gains electrons, the other loses electrons.

d.substances that give up electrons are reduced.

_____13. Which of the following represents a double-displacement reaction between sodium chloride and silver fluoride?

a.NaCl + AgFNaAgF + Cl2 c.NaCl + AgF Ag + NaClF

b.NaCl + AgFNaF + AgCl d.NaCl + AgFNaF + Cl2+ Ag

_____14. Pieces of molecules that have one or more electrons available for bonding are

a.radicals. c. neutrons.

b.reactants. d. protons.

_____15. A synthesis reaction between magnesium (Mg) and oxygen (O2) might produce

a.Mg2. c. MgO.

b.O4. d. MgCO2.

In the space provided, write the letter of the term or phrase that best matches each description.

_____16. CH4+ 2O2CO2+ 2H2O

_____17. 2NH3N2+ 3H2

_____18. 2NaCl + H2SO4Na2SO4+ 2HCl

_____19. Fe + S FeS

_____20. 2Li + 2H2O 2LiOH + H2

Section: Chemical Equations

_____21. In a balanced chemical equation, the mass of the reactants is equal to the

a.atoms in a molecule. c. volume of the reactants.

b.atomic mass of the elements. d.mass of the products.

_____22. What coefficient is missing in C2H4 + (?)O2 2CO2 + 2H2O?

a.2 b. 3 c. 4 d. 5

_____23.In the reaction 3CuCl2 + 2Al  2AlCl3 + 3Cu, how many moles of Al react with 3 moles of CuCl2?

a.1 mol b. 2 mol c. 3 mol d.4 mol

_____24.If you use 3 mol of O2 in the reaction 2Mg + O2 2MgO, how many moles of Mg are needed?

a.1 mol b. 2 mol c. 4 mol d.6 mol

_____25.Give the mole ratio for the following equation:
Zn+2HCl ZnCl2+H2.

a.1:1:1 b. 1:2:1 c. 1:2:1:1 d.1:2:2:2

_____26.In the reaction 2H2O  2H2 + O2, if you start with 4 mol of water, how many moles of hydrogen gas are formed?

a.2 mol b. 4 mol c. 6 mol d.8 mol

_____27.Which of the following equations is not balanced?

a.Fe + S FeS c. 2Mg + O2 2MgO

b.KOH + HClKCl + H2O d. NaCl + H2SO4 Na2SO4 + HCl

Section: Reaction Rates and Equilibrium

_____28.At higher temperatures, food cooks faster because particles of food

a.take up less space. c. collide more often.

b.increase in number. d. come into contact with water.

_____29. Catalysts that slow reactions are called

a.inhibitors. c. balanced.

b.substrates. d. endothermic.

_____30. A slow reaction is likely to occur when the reactants have ______temperatures and ______surface areas.

a.high, small c. high, large

b.low, small d. low, large

_____31.Which is not true of catalysts?

a.They are used up in a reaction. c.They can slow down a reaction.

b.They can speed up a reaction. d.They can be reused.

_____32.Raising the temperature of a system favors the reaction that

a.absorbs energy. c. releases energy.

b.is exothermic. d. is exergonic.

_____33.Which is not true of enzymes?

a.They are catalysts. c. They are affected by temperature.

b.They are proteins. d. They are inefficient.

_____34.When a chemical reaction and its reverse occur at the same time and rate, the reaction is said to be in

a.equality. c. imbalance.

b.equilibrium. d. redox.

_____35.According to Le Châtelier’s principle, opening a soda can produces bubbles because which of the following changes occurs in the bottle?

a.Pressure increases. c. Pressure decreases.

b.Temperature increases. d. Temperature decreases.

_____36.All of these are likely to speed up the rate of a reaction except

a.decreasing the surface area. c. increasing the temperature.

b.increasing the pressure. d. adding a catalyst.