Thermodynamics

Question 1

Define a Thermodynamic System

Answer 1

The particular thing or part of the physical universe that we choose to study

Question 2

Define Boundary

Answer 2

The real or imaginary separation between the system and the rest of the universe. If clearly defined the system can exchange energy and matter.

Question 3

Define Surroundings

Answer 3

The part of the universe that is outside the system (everything else)

Question 4

Define Universe

Answer 4

The system and surroundings

Question 5

Define Open System

Answer 5

Can exchange both energy and matter with the surroundings (both energy and matter can cross the boundary)

Question 6

Define a closed system

Answer 6

Can exchange energy, but not matter, with the surroundings

Question 7

Define an isolated system

Answer 7

Cannot exchange energy or matter with the surroundings

Question 8

Define State variables (aka state variables)

Answer 8

Describes the conditions of a system. Does not depend on how that state was achieved (path independent).

Question 9

Give some examples of state variables

Answer 9

Examples: temperature, pressure, volume, density, mass, and concentration.

Question 10

Define Intensive Variables

Answer 10

Independent of the size of the system (size does not matter)

Question 11

Define extensive variable

Answer 11

Dependant on size of the system (changes with size and only size, not volume)

Question 12

What are some examples of intensive variables?

Answer 12

Pressure, temperature, density, number of moles, molar mass, and concentration.

Question 13

What are some examples of extensive variables?

Answer 13

Volume, mass, and energy.

Question 14

How do you change extensive to intensive and vise versa?

Answer 14

Ext / Int = Ext
Ext / Ext = Int

You cannot change an intensive variable to extensive.

Question 15

How do you change extensive to intensive and vise versa?

Answer 15

Ext / Int = Ext
Ext / Ext = Int

You cannot change an intensive variable to extensive.

Question 16

Define Equilibrium

Answer 16

When properties of a system in a certain state are independent of time (stable).

Question 17

What is the Ideal Gas Law

Answer 17

Describes the relationship among thermodynamic state variables of ideal gases at equilibrium.

PV =nRT

Question 18

What is an ideal gas?

Answer 18

Non-interacting
Point particles
In random motion
Undergoing perfectly elastic conditions

Question 19

What does it mean to be non-interacting?

Answer 19

Do not exert forces on each other (other than collisions)

Question 20

What is a point particle?

Answer 20

Particles that have no volume

Question 21

What does it mean to have a perfectly elastic collision?

Answer 21

Energy is conserved

Question 22

What is the First Law of Thermodynamics?

Answer 22

Change in E = q + w

Question 23

How is energy transferred?

Answer 23

Heat (q) and/or work (w)

Question 24

How is energy transferred?

Answer 24

Heat (q) and/or work (w)

Question 25

How do you calculate work? Aka what is the formula?

Answer 25

W = -Pext x change in volume

Question 26

How does q become - or + ?

Answer 26

When heat is absorbed (q+), and when lost (q-)

Question 27

When is work + and - ?

Answer 27

When work is done ON the system W > 0 When work is done BY the system W < 0

Question 28

What is the difference between state functions and path variables ?

Answer 28

State functions DO NOT depend on the path. Path variables DO depend on the path (ex: work and heat)

Question 29

What does isothermal mean?

Answer 29

Temperature remains constant (Tf = Ti)

Question 30

What does it mean to have an ideal gas in a closed system?

Answer 30

T is directly proportional to E (change in T = change in E)

Question 31

How do you find out work with a P vs. V graph?

Answer 31

By calculating the area under the curve. (May have to integrate with curve)