CHEM111 CHAPTER 13-14

Question 1

Reaction rate

Answer 1

Speed of a chemical reaction; occur when atoms or molecules collide but only when there is enough energy and at an orientation that allows the rearrangement to take place

Question 2

Collision theory

Answer 2

Theory that states that for a reaction to occur, reactant particles must collide and collision must have a certain minimum amount of energy; Activation Energy

Question 3

3 major factors that affect collisions and rates of chemical reaction:

Answer 3

• Concentration
• Temperature
• Energy changes

Question 4

Factors that affect reaction rates (4):

Answer 4

• Physical state: solid, liquid, gas
• State of subdivision, size of particles
• Solid reactions occur at surfaces which increases surface area and increases rate of reaction
• Gas phase reactions tend to react faster than solid or liquid phase

Question 5

Effects of concentration (2):

Answer 5

• Low concentration = fewer collisions
• High concentration = more collisions

Question 6

Effects of increased temperature (2):

Answer 6

• Lower temperature, = less kinetic energy = fewer collisions
• Higher temperature = more kinetic energy = more collisions

Question 7

Transition state

Answer 7

The highest energy arrangement of atoms that occurs during a chemical reaction

Question 8

Activation energy

Answer 8

The energy barrier for a reaction. This energy determines how quickly a reaction occurs. Reaction rates depend on the concentration and the activation energy

Question 9

Catalysts

Answer 9

Substance that when added to a chemical reaction speeds up rate of reaction but is itself unchanged after the reaction is completed (Catalysts lower activation energy needed of a reaction and provides an alternate pathway for reaction)

Question 10

Equilibrium reaction

Answer 10

Reactions that can go in the forward direction and also backwards represented by a double arrow. Side of equilibrium with lower energy has greater concentration and vice versa

Question 11

How does the changing concentrations affect rate of for the forward and reverse reactions

Answer 11

As the concentration of reactants decreases expect the rate of the forward reaction to decrease. As the concentration of the products increases, expect the rate of the reverse reaction to increase

Question 12

The Equilibrium equation

Answer 12

Just remember that right side of equation goes on numerator and left side is bottom and its the one with [][]/[][] with powers raised

Question 13

Solubility product

Answer 13

The equilibrium constant for the solution of a slightly soluble ionic compound

Question 14

Le Chatelier’s Principle

Answer 14

States that if one or more particular substance (reactant or product) is added to the system, equilibrium will shift to use up that substance

Question 15

A + B + heat = C is an example of

Answer 15

Endothermic

Question 16

E + F = G + heat is an example of

Answer 16

Exothermic

Question 17

Shifts in equilibrium (3):

Answer 17

• Adding to an equilibrium pushes it towards the other side
• Heating shifts an equilibrium towards the higher energy side
• High pressure shifts equilibria towards the side with fewer moles of gas

Question 18

Oxidation - Reduction reactions

Answer 18

A chemical change in which one species loses electrons (oxidation), while another gains electrons (reduction); also called redox reactions

Question 19

Oxidation

Answer 19

Loss of electrons

Question 20

Reduction

Answer 20

The gain of electrons

Question 21

Oxidizing agent

Answer 21

Takes electrons

Question 22

Reducing agent

Answer 22

Loses electrons

Question 23

Types of redox reactions (4):

Answer 23

• Disproportionation reactions
• Metals as reducing agents; reactions of metals with acids, reactions of metals with aqueous metal salts
• Reaction of two nonmetals
• Reaction of metal salts and non metals in acid solution

Question 24

Disproportionation reactions

Answer 24

Reactions in which atoms of a single element undergo both oxidation and reduction

Question 25

Metals as reducing agents

Answer 25

Metallic elements that tend to lose electrons to form cations = act as reducing agents

Question 26

Half reactions

Answer 26

A chemical equation that shows only the reduction or oxidation component of a reaction; half reaction uses e^- to represent electron in either the reactants or the products

Question 27

Combustion reactions

Answer 27

Reactions that involve molecular oxygen; most elements react with oxygen to form oxides

Question 28

Metal displacement reaction

Answer 28

A reaction between two metals in which one metal is oxidized to its ionic form while the other metal ion is reduced to its elemental form

Question 29

Voltaic cells

Answer 29

Electrochemical cell that uses spontaneous chemical reactions to create a flow of electrons (electricity)

Question 30

Electrolytic cells

Answer 30

Electrochemical cells that use electricity to cause a nonspontaneous chemical reaction to occur

Question 31

Batteries

Answer 31

A device that produces electric current through a redox reaction in which the two half-reactions occur at separate sites; also called an electrochemical cell

Question 32

Electrodes

Answer 32

The metal bars where the redox reactions take place

Question 33

Negative electrode/anod

Answer 33

Electrode where oxidation occurs

Question 34

Positive electrode/cathode

Answer 34

Electrode where reduction occurs

Question 35

Salt bridge

Answer 35

Where ions from the anode and cathode solutions flow through to prevent build up of negative charge in cathode compartment

Question 36

Half cell

Answer 36

Where electricity is produced by the movement of electrons through wire from anode half cell to cathode half cell

Question 37

Electrical potential

Answer 37

The driving force for the flow of electrons

Question 38

Voltage

Answer 38

The unit of electrical potential energy

Question 39

Electroplating

Answer 39

Technique that produces a thin layer of a metal such as gold, silver, copper, or chromium on the outside surface of another material

Question 40

Fuel cells

Answer 40

A device that converts the energy of a combustion reaction directly into electrical energy by separating the oxidation and reduction of half-reactions

Question 41

Two general methods for balancing oxidation-reduction equations:

Answer 41

• Ion-electron or half reaction method: best for aqueous redox reactions, and balancing net ionic redox equations
• Oxidation number method