Chapter 3 - Thermodynamics

Question 1

Temperature vs Heat

Answer 1

Temperature: average kinetic energy of particles that make up the substance

Heat: transfer of thermal E from hotter object to colder

Question 2

What is thermal equilibrium?

Answer 2

No net heat flowing between two objects in thermal contact

*temps are equal

Question 3

Thermal expansion equation

Answer 3

∆L = aL∆T

∆L = change in length
L = original length
a. = coefficient of linear expansino

Question 4

Volumetric expansion

Answer 4

∆V = ßV∆T

Question 5

First Law of thermodynamics as an equation for internal energy

Answer 5

∆U = Q - w

Change in total internal energy of a system

IS EQUAL TO:

Amount of energy transferred in form of heat TO THE SYSTEM

MINUS:

The amount of energy transferred FROM THE SYSTEM in the form of work

Q= energy transfered as heat (into system)
W = work done (by system)

Question 6

What is the SI unit for heat?

Answer 6

joule (J)

1Cal = 10^3 cal = 4184 J = 3.97 BTU

Question 7

The means of heat transfer

Answer 7

Conduction: directed through molecular collisions

Convection: physical motion of a fluid over a material (liquids and gases)

Radiation: electromagnetic waves

Question 8

List terms for phase changes

Answer 8

Fusion/melting: solid to liquid
Solidification/freezing: liquid to solid

Evaporation/vaporization: liquid to gas

Condensation: gas to liquid

Sublimation: solid to gas

Deposition: gas to solid

Question 9

Equation used when no temp change during phase change

Answer 9

q = mL

q = amount of heat gained or lost from material

m = mass of substance

L = heat of transformation (latent heat)

Question 10

What does the 1st law of thermodynamics reduce to when the process is :

1. Isothermal
2. Adiabatic
3. Isobaric
4. Isovolumetric (isochoric)

Answer 10

1. ∆U = 0:
   Q = W
2. Adiabatic: Q = 0 (no heat exchange)

∆U = -W

3. Isobaric …no special form
4. Isochoric: W=0

∆U = Q

Question 11

What are the units of entropy?

Answer 11

J/ mol*K

Question 12

If a gas expands is it doing work or is work done on it

Answer 12

Expansion (work being done by the gas )…decreases internal energy

COmpression: work done ON the gas

(Increases internal energy)