Physics-Thermodynamics

Question 1

What is the zeroth law of thermodynamics?

Answer 1

objects are in thermal equilibrium when they are at the same temperature

◦ There's no net exchange of heat energy

Question 2

Define temperature

Answer 2

Temperature is related to the average kinetic energy of the particles

Question 3

Define thermal expansion

Answer 3

a change in the temperature of most solids results in a change in their length

 ◦ Δ L = αLΔ T

Question 4

Define volumetric expansion

Answer 4

a change in the temperature of most liquids results in a change in their volume

◦ Δ V = βVΔ T

Question 5

What is the melting point and boiling point in F/C/K?

Answer 5

Melting point: 32/0/273

Boiling point: 212/100/373

Question 6

What is an isolated system?

Answer 6

does not exchange matter or energy with the surroundings

Question 7

What is a closed system?

Answer 7

exchanges energy but not matter

Question 8

What is an open system?

Answer 8

exchanges both matter and energy

Question 9

What is a state function?

Answer 9

pathway independent and are not defined by a process

◦ Pressure, density, internal energy, enthalpy, entropy

Question 10

What is a process function?

Answer 10

describes the pathway from one equilibrium state to another

◦ Work and heat

Question 11

What is the 1st law of thermodynamics?

Answer 11

The total energy in the universe can never decrease or increase

◦ Δ U = Q - W

Question 12

Define heat?

Answer 12

process of energy transfer between 2 objects at different temperatures that occurs until they have reached the same temperature

Question 13

Define conduction

Answer 13

direct transfer of energy through molecular collisions

◦ Metals are best heat conductors, gases are worst

Question 14

Define convection

Answer 14

transfer of heat by the physical motion of a fluid

◦ Only liquids and gases

Question 15

Define radiation

Answer 15

transfer of energy by electromagnetic waves through a vacuum

Question 16

Define specific heat (c)

Answer 16

the amount of energy necessary to raise one gram of a substance by one degree Celsius or Kelvin

Question 17

What is the specific heat of water?

Answer 17

1 cal/g x K

Question 18

What is the formula for specific heat?

Answer 18

q = mc∆t

Question 19

What is heat of transformation?

Answer 19

during a phase change, heat energy causes changes in the particles’ potential energy and energy distribution (entropy), but not kinetic energy. Therefore there is no change in temperature

Question 20

What equation is used when temperature does not change during a phase change?

Answer 20

q = mL

‣ Q = heat gained/lost, m = mass, L = heat of transformation/latent heat

Question 21

What occurs during a thermodynamic process?

Answer 21

a specific variable is held constant

Question 22

Define isothermal process

Answer 22

∆T = 0 –> U = 0

Question 23

Define adiabatic process

Answer 23

Q = 0

Question 24

Define isobaric process

Answer 24

∆P = 0

Question 25

Define isochoric process

Answer 25

∆V = 0 –> W = 0

Question 26

What is the 2nd law of thermodynamics?

Answer 26

Energy will be dispersed from an object with a higher temperature to an object with a lower temperature until they are both in thermal equilibrium

Question 27

Define entropy

Answer 27

measure of how much energy has spread out or how spread out energy has become

Question 28

What is the equation for change in entropy?

Answer 28

∆S = Qrev / T

◦ S = change in entropy, Qrev = heat that is gained or lost, T = temp in Kelvin
◦ Units: J/mol x K

Question 29

What happens when energy is put into/taken out of a system?

Answer 29

Entropy increases/Entropy decreases