Chapter 7

Question 1

What two things play an important role in determining the extent and speed of a chemical reaction?

Answer 1

1) Thermodynamics, which deals with energy changes in chemical reactions
2) Kinetics, which describes the rate or speed of a chemical reaction

Question 2

Thermodynamics

Answer 2

study of energy, work, and heat

Question 3

3 Basic laws of thermodynamics?

Answer 3

1) energy cannot be created or destroyed, only converted from one form to another
2) the universe spontaneously tends toward increasing disorder or randomness
3) the disorder of a pure, perfect crystal at absolute zero is zero 0 (Kelvin)

Question 4

Average kinetic energy of atoms or molecules does what with increasing temperature?

Answer 4

Increases

Question 5

What happens when some collisions of molecules occur with sufficient energy?

Answer 5

can break bonds in molecules

Question 6

What can happen when a reactant bond is broken?

Answer 6

new bonds may be formed and products result

Question 7

System?

Answer 7

contains the process under study

Question 8

Surroundings?

Answer 8

encompass the rest of the universe (system)

Question 9

Heat

Answer 9

transfer of thermal energy to the surroundings; sometimes consider heat flow

Question 10

Calorimetry

Answer 10

Experimental strategies for measuring temperature change and calculating heats of reactions

Question 11

Exothermic reaction

Answer 11

Releases energy to the surroundings (surroundings become warmer)
representative with a negative sign

Question 12

Endothermic reaction

Answer 12

absorbs energy from the surrounds (surrounding become colder)
representative with a positive sign

Question 13

Enthalpy

Answer 13

term used to represent heat and is symbolized as H

Question 14

If H reactants > H products, what is H?

Answer 14

H must be negative and the reaction is exothermic

Question 15

If H reactants < H products, what is H?

Answer 15

H must be positive and the reaction is endothermic

Question 16

Entropy

Answer 16

A measure of the randomness of a chemical system.

Question 17

Symbol for entropy?

Answer 17

symbol S

Question 18

Free Energy

Answer 18

symbol G, represents the combined contribution of the enthalpy and entropy values for a chemical reaction

Question 19

4 situations of G

Answer 19

• H (neg) & S (pos), G is always pos, regardless of temp
• H (pos) & S (neg), G is always neg, regardless of temp
• H (pos) & S (neg), G depends on temp
• H (neg) & S (neg), G depends on temp

Question 20

specific heat

Answer 20

number of calories (cal) of heat needed to raise the temperature of 1 gram (g) of the substance 1 degree Celsius (c).

Question 21

Quantity of heat absorbed or released by the reaction (Q)?

Answer 21

mass of solution in the calorimeter (Ms), (X)
specific heat of the solution (SHs), (X)
change in temperature (Ts) of the solution

Question 22

Fuel Value

Answer 22

is the amount of energy per g of food

Question 23

Nutritional Calories (Cal)

Answer 23

equivalent to one kilo-calorie (1000 cal), known as the large Calorie

Question 24

bomb caloriemeter

Answer 24

measurement of the fuel value (Cal) of foods

Question 25

Effective collision

Answer 25

producing product molecules (requires sufficient energy and, in the case of complex molecules, the proper orientation of reaction molecules.

Question 26

Activation energy

Answer 26

Ea, minimum amount of energy required to initiate a chemical reaction

Question 27

Activated complex

Answer 27

reaction proceeds from reactants to products through an extremely unstable state

Question 28

Factors that affect reaction rate

Answer 28

1) structure of the reacting species 2) molecular shape and orientation 3) the concentration of reactants 4) the temperature of reactants 5) the physical state of reactants 6) the presence of a catalyst

Question 29

Catalyst

Answer 29

substance that increases the reaction rate

Question 30

K

Answer 30

rate constant @ specific temp

Question 31

rate laws

Answer 31

rate being equal to the rate constant multiplied by the reactant concentration raised to an exponent

Question 32

equilibrium reactions

Answer 32

reactions that do not go to completion. no further obvious change is taking place, measurable quantities of reactants and products remain

Question 33

reversible reaction

Answer 33

process that can occur in both directions

Question 34

dynamic equilibrium

Answer 34

situation in which the rate of the forward process in a reversible reaction is exactly balanced by the rate of the reverse process

Question 35

equilibrium constant

Answer 35

Keq = products/reactants

Question 36

Is Keq temp dependent or not?

Answer 36

temp dependent

Question 37

what temp is equilibrium constant reported at?

Answer 37

25 degree C

Question 38

Molarity?

Answer 38

(mol/L)

Question 39

LeChatelier's principle

Answer 39

if a stress is placed on a system at equilibrium, the system will respond by altering the equilibrium composition in such a way to minimize the stress

Question 40

Add product, equilibrium shifts to the ?

Answer 40

Left

Question 41

Add reactant, equilibrium shifts to the ?

Answer 41

Right

Question 42

N2(g) + 3H2 (G) 2NH3 (g) + kcall is a what reaction?

Answer 42

exothermic

Question 43

How does equilibrium shift when heat is added to exothermic reaction?

Answer 43

will shift left

Question 44

How does equilibrium shift when heat is removed from an exothermic reaction?

Answer 44

will shift right

Question 45

How does equilibrium shift when heat is added to endothermic reaction?

Answer 45

will shift right

Question 46

How does equilibrium shift when heat is removed from an endothermic reaction?

Answer 46

will shift left

Question 47

39 kcal + 2N2(g) + O2(g) 2N2O(g) is what type of reaction?

Answer 47

endothermic reaction

Question 48

Pressure on an equilibrium reaction does what to reaction

Answer 48

shifts to the side that has the least amount of mole

Question 49

pressure released on an equilibrium reaction does what to the reaction

Answer 49

shifts to the side that has the most amount of moles

Question 50

Catalyst do what to an equilibrium reaction?

Answer 50

no change