CH. 2.1 - HEAT, WORK AND ENERGY

Question 1

What is Thermodynamics?

Answer 1

The study of energy changes involved in physical and chemical processes

Question 2

What is an example of a thermodynamic physical process?

Answer 2

heating and cooling of substances, phase changes, etc.

Question 3

What is an example of a thermodynamic chemical process?

Answer 3

chemical reactions

Question 4

What is thermochemistry?

Answer 4

subject that investigates the heat flow that occurs during thermodynamic reactions

Question 5

TRUE OR FALSE: rates of most chemical reactions DECREASE as temperature INCREASES

Answer 5

FALSE: the rate of most chemical reactions will INCREASE as temperature INCREASES (directly related!)

Question 6

What is heat flow?

Answer 6

the transfer of thermal energy in the process being studied

Question 7

Where does heat always flow in a thermodynamic process?

Answer 7

always flows from the warmer object to the cooler object

Question 8

What is the “system” in a process?

Answer 8

the part of the reaction that one wants to study

Question 9

What is the “system” in a chemical reaction?

Answer 9

the reactants (chemicals)

Question 10

What are the “surroundings” in a process?

Answer 10

the remaining parts of the reaction that can interact with the system

Question 11

What is an example of surroundings in a chemical reaction?

Answer 11

The flask, the air around it (if it an open system), any other material that has contact with the system.

Question 12

What are the 3 types of systems?

Answer 12

1. Open System
2. Closed System
3. Isolated System

Question 13

What does it mean to have an Open System?

Answer 13

an open system exchanges both MATTER and ENERGY with its surroundings

Question 14

What does it mean to have a Closed System?

Answer 14

a closed system exchanges ENERGY but not matter with its surroundings

Question 15

What does it mean to have an Isolated System?

Answer 15

an isolated system doesn’t exchange anything with its surroundings

Question 16

What is Energy?

Answer 16

The capacity to do work

Question 17

What are 4 types of energy?

Answer 17

1. Heat (thermal energy)
2. Kinetic Energy
3. Potential Energy
4. Chemical Energy

Question 18

What is Work?

Answer 18

the product of a force acting on an object at a distance

Question 19

What is Heat Capacity?

Answer 19

the measure of how many J are required to change the temp. of an OBJECT by ONE degree

Question 20

What is SPECIFIC Heat Capacity?

Answer 20

the measure of how many J are required to change the temp. of one mass unit of a SUBSTANCE by ONE degree

Question 21

What happens in an endothermic reaction?

Answer 21

a system ABSORBS energy from the surroundings

Question 22

Will a system warm up or cool down in an ENDOTHERMIC reaction

Answer 22

Warm up

Question 23

In an ENDOTHERMIC reaction, is the q (+) or (-) ?

Answer 23

positive: +q

Question 24

What happens in an exothermic reaction?

Answer 24

the system RELEASES energy to the surroundings

Question 25

Will a system warm up or cool down in an EXOTHERMIC reaction

Answer 25

Cool down

Question 26

In an EXOTHERMIC reaction, is the q (+) or (-) ?

Answer 26

negative: -q

Question 27

What does thermal equilibrium mean?

Answer 27

the number of joules lost by the warmer object must = the number of joules gained by the cooler object

Question 28

What is the final goal of thermal equilibrium?

Answer 28

For both objects/substances to be the same temperature

Question 29

What is an intensive/intrinsic property?

Answer 29

A physical property that does NOT depend on the amount of material in a system

Question 30

What is an example of an intensive/intrinsic property?

Answer 30

temperature

Question 31

What is an extensive/extrinsic property?

Answer 31

A physical property or quantity whose value is proportional to the size of the system its for

Question 32

What are examples of Extensive/extrinsic properties?

Answer 32

mass, length, enthalpy, entropy, etc.

Question 33

What is a state function?

Answer 33

a property whose value depends ONLY on the current state of the system; it does NOT matter how the state of the system was reached

Question 34

What are 2 examples of state functions

Answer 34

1. Internal Energy
2. Enthalpy

Question 35

Are heat and work state functions? Why or why not?

Answer 35

NO: because they are path dependent

Question 36

What is the 1st Law of Thermodynamics?

Answer 36

the total energy of a system and its surroundings is conserved (E before = E after)

Question 37

What is Internal Energy?

Answer 37

the sum of all the kinetic and potential energies of all the atoms and molecules in a system

Question 38

What is expansion/how does it work?

Answer 38

the expanding gas (the system) is doing work on the surroundings

(the value of Work is (-))

Question 39

Why is work (-) in expansion?

Answer 39

because work energy has been used, therefore it was removed from the system

Question 40

What is compression/how does it work?

Answer 40

the surroundings are doing work on the system.

The value of W is (+)

Question 41

Why is work positive in compression?

Answer 41

because the system has gained work energy

Question 42

If a process has NO compression or expansion, what happens to Work and Volume?

Answer 42

• W = 0
• There is no volume change

Question 43

When ΔE > 0, what happens to the internal energy of the system?

Answer 43

The internal energy INCREASES

Question 44

When ΔE < 0, what happens to the internal energy of the system?

Answer 44

The internal energy DECREASES