Thermodynamics

Question 1

What is Thermodynamics?

Answer 1

Thermodynamics: A study of energy transfer and the relationship between properties of substances.
Revolves around Thermal Motion, Thermal Energy and Temperature.

Question 2

What is Thermal motion?

Answer 2

Thermal motion: Particles and atoms constant movement are influenced by changes in temperature in a proportional matter .

Question 3

What is Thermal Energy?

Answer 3

Thermal Energy: The sum of all kinetic energy (rotational, vibrational) and translational energy of particles. It is used to describe the power of the thermal motion.

Question 4

What is Temperature (T)?

Answer 4

Temperature (T): A physical quantity describing the internal thermal state of an object. The degree of thermal energy is the temperature.

Question 5

Change in Temperature → Change in _______ _____ → Change in Thermal Energy

Answer 5

Change in Temperature → Change in Thermal Motion → Change in Thermal Energy

Question 6

Temperature Scales - Kelvin

Answer 6

Kelvin (=Absolute, Fahrenheit) scale (K): Fixed points are 0K (absolute zero, no values below this point) and 100K (human body temperature).
(SI Unit)

Question 7

Temperature Scales - Celsius

Answer 7

Celsius scale (℃): Fixed points are 0℃ (melting point of ice) and 100℃ (boiling point of H2O)

Question 8

Conversion Formula between Celsius and kelvin:

Answer 8

𝑡/℃=𝑇/𝐾−273.15

Question 9

Define Heat (Q):

Answer 9

Heat (Q):The process of energy transfer between two interacting objects of different thermal energies. The object with higher temperature will transfer energy in form of heat to the other object.

Question 10

What is the SI unit of Heat (Q)?

Answer 10

Heat (Q) - SI unit: J

Question 11

Define Heat capacity (C):

Answer 11

The ratio between heat transfer and change in temperature (∆𝑇).

Question 12

Formula for Heat Capacity (C):

Answer 12

𝐶= 𝑄/∆𝑇

Question 13

Unit for Heat Capacity (C):

Answer 13

Unit:J/K

Question 14

Define Specific Heat capacity (Cs):

Answer 14

The heat capacity of a specific body. It depends on the body size and material.

Question 15

Formula for Specific Heat Capacity (Cs):

Answer 15

C𝑠= 𝐶/𝑚

Question 16

Unit for Specific Heat Capacity (C):

Answer 16

Unit:J/kg∙K

Question 17

What is Thermal expansion?

Answer 17

Thermal expansion: Increase in thermal motion and energy of a body, may result in thermal expansion. This can increase the length and volume of a body. Usually as the temperature increase, bodies expand. Vise versa, bodies shrink.

Question 18

States of matter: The body (material) can exist in _(how many?) different states of matter

Answer 18

States of matter: The body (material) can exist in 3 different states of matter
(There are actually 5 but this is not our topic)

Question 19

Define the 3 different States of Matter by Volume and Shape.

Answer 19

Solid: Well defined volume and shape of the body
Liquid: Defined volume, but shape depends on the container
Gas: No definite volume or shape. The body takes the volume and shape of its container

Question 20

What is a Phase transition?

Answer 20

Phase transition: The change of a body from one state to another.

Question 21

What are the different Phase Transitions?

Answer 21

Melting↔Freezing
Evaporation↔Condensation
Sublimation

Question 22

What is Specific Latent Heat?

Answer 22

Specific latent heat (L): During a phase transitioning, the released/absorbed heat (Q) divided by the mass (m) of the body, is called the specific latent heat.

Question 23

Specific latent heat (L) - Unit:

Answer 23

Specific latent heat (L) -Unit: J/kg

Question 24

What is the formula for Specific latent heat (L)?

Answer 24

𝐿= 𝑄/𝑚

Question 25

What is Specific heat of of fusion (Lf)?

Answer 25

Specific heat of of fusion (Lf): In case of melting, the specific amount of heat needed for 1kg body to move from a solid to liquid state.

Question 26

What is Specific heat of of vaporization (Lv)?

Answer 26

Specific heat of vaporization (Lv): In case of boiling, the specific amount of heat needed for 1kg body to move from a liquid to gas state

Question 27

How can we define amount of substance (From chemistry)?Units?

Answer 27

Amount of substance (n): 1 mole of a body contains 6.02*1023 mol^-1 number of particles. Unit: mole

Question 28

What is Avogadro’s Constant (Na)

Answer 28

NA = 6.02 ∙ 1023 mol^-1

Question 29

number of particles (N) - Definition and Formula (Chemistry)

Answer 29

The number of particles (N) equals The relationship between the amount of substance (n) and Avogadro’s Number (Na)
Formula - N=n∙𝑁a

Question 30

What is an Ideal gas?

Answer 30

Ideal gas: A gas consisting of random moving point particles, which have perfect elastic collisions. They only move by translation, thus the thermal energy is proportional to the kinetic translational energy.

Question 31

Formula for the Ideal Gas law

Answer 31

pV=nRT
T = temperature (K)
R (universal gas constant) = 8.314 J/(mol*K)

Question 32

What is an Isobaric Process?

Answer 32

Isobaric process: Pressure p stays constant

Question 33

What is an Isothermal process?

Answer 33

Isothermal process: Temperature T stays constant

Question 34

What is an Isochoric process?

Answer 34

Isochoric process: Volume V stays constant

Question 35

1st law of Thermodynamics - Formula

Answer 35

1st law of Thermodynamics : ∆𝑈=𝑄 −𝑊
∆U = Internal energy
Q = Heat (J)
W = Work (J)

Question 36

2nd law of Thermodynamics - Formula

Answer 36

2nd law of Thermodynamics:

∆𝑆𝑡𝑜𝑡𝑎𝑙=∆𝑆𝑠𝑦𝑠𝑡𝑒𝑚+∆𝑆𝑠𝑢𝑟𝑟𝑜𝑛𝑑𝑖𝑛𝑔 >0

Question 37

3rd law of Thermodynamics - Definition

Answer 37

As the temperature approaches absolute 0 (0K), the entropy of a system goes towards a constant value.