Thermo and Kinetics

Question 1

Thermodynamics

Answer 1

The study of energy and its relationship to chemical systems. Deals with rxn spontaneity, but NOT rate.

Question 2

System

Answer 2

The piece of the universe that is the focus of the study.

Question 3

Surroundings

Answer 3

Everything outside the system.

Question 4

Open Systems

Answer 4

Exchange mass and energy with surroundings.

Question 5

Closed systems

Answer 5

Exchange energy but not mass.

Question 6

Isolated systems

Answer 6

No exchange of energy or mass.

Question 7

Extensive properties

Answer 7

Change with size of the system. (Volume)

Question 8

Intensive properties

Answer 8

Unaffected by size of the system. (Temperature, pressure)

Question 9

Temperature

Answer 9

How fast the molecules of a substance are moving. Can be translational, rotational, or vibrational.

Question 10

Thermal energy

Answer 10

The sum of the 3 energies that describe temperature.

Question 11

Kinetics

Answer 11

The study of the speed of reactions. Deals with rxn rate, but NOT spontaneity. Determined by Ea.

Question 12

Intermediates

Answer 12

Molecules that are created as the product of one step of a rxn and used as the reactants of the next step.

Question 13

Rate Law

Answer 13

Expression for the rxn rate.

Question 14

Reaction order

Answer 14

The exponent of that reactant in the rate law.

Question 15

Rate determining step

Answer 15

The slow step of the rxn. The step.

Question 16

Catalyst

Answer 16

Increases the rate of the rxn without being changed or used up.

Question 17

State function

Answer 17

Irrelevant of the path there, they describe the nature of the system. (Temperature)

Question 18

Internal energy

Answer 18

The total energy of molecules.

Question 19

Heat

Answer 19

Spontaneous transfer of energy from a warmer substance to a colder substance.

Question 20

Zeroth law of thermodynamics

Answer 20

Two systems in equilibrium with a third system are also in equilibrium with each other.

Question 21

Conduction

Answer 21

Thermal energy transfer through molecular collisions: Requires actual, physical contact.

Question 22

Convection

Answer 22

Thermal energy transfer through fluid means. (Liquids and gases). Pressure or density gradients push warm to cold.

Question 23

Radiation

Answer 23

Thermal energy transfer through electromagnetic waves. (Does not need a medium)

Question 24

Work

Answer 24

Any energy transfer that is not heat.

Question 25

Second Law of thermodynamics

Answer 25

Entropy of an isolate system will never decrease.

Question 26

First law of thermodynamics

Answer 26

Total energy of the system and its surroundings is always conserved. There is no net gain or loss. (ΔU = w{nonPV} - w{PV} + q) in other words W + q = Etotal

Question 27

Enthalpy

Answer 27

The measure of units of energy. Described in the equation (ΔH= ΔU +ΔPV). State function.

Question 28

Standard enthalpy of formation

Answer 28

Change in enthalpy of a substance required to create one mole of a compound from the reactants in their standard states.

Question 29

Endothermic reaction

Answer 29

Reaction with a positive enthalpy change. (+ΔH). Heat flow to the system.

Question 30

Exothermic reaction

Answer 30

Reaction with a negative enthalpy change. (-ΔH). Heat flow into the surroundings.

Question 31

Anabolic

Answer 31

Build big molecule from small molecules. (Endothermic)

Question 32

Catabolic

Answer 32

Breaks a big molecule into smaller molecules. (Exothermic)

Question 33

Entropy

Answer 33

Nature's tendency towards disorder. The most likely arrangement in a system. State function.

Question 34

Third Law of thermodynamics

Answer 34

Any pure element or compound in solid form at absolute zero and internal equilibrium has no entropy.

Question 35

Gibbs free energy

Answer 35

Entropy change in both the system and surroundings. (ΔG = ΔH -TΔS)system.

Question 36

Hess's law of heat summation

Answer 36

In a multi step rxn, the sum of enthalpies for each step is equal to the total enthalpy change.

Question 37

Transition state

Answer 37

"peak of the hill" in a graph of a rxn. Represents the point at which bonds of reactants break, and bonds of products form.

Question 38

Chemical equilibrium

Answer 38

When the rate of the forward rxn = the rate of the reverse rxn. The point of greatest entropy.

Question 39

Le Chatelier's principle.

Answer 39

When a system at equilibrium is stressed, it will shift in the direction to remove the stress.. Types of stresses the system responds to 1. Add or subtract a product or reactant. 2. Change in P or V of system. 3. Heat or cool the system.