Thermodynamics

Question 1

What does themodynamics study

Answer 1

Transformation of energy of one form to another. It places attention on the system and the relation it has with its surrounding

Question 2

What is a system and what is a surrounding

Answer 2

•System-all material included inside a closed surface but it can be also ideal surface with no real barriers
•Surrounding-everything that is not inside the system’s surface

Question 3

What types of systems exist

Answer 3

1. Open-exchanges matter and energy
2. Closed-exchanges energy
3. Adiabatic-Exchanges energy but not in form of heat
4. Isolated-can not exchange energy or matter with the surrounding

Question 4

What are macroscopic variables

Answer 4

Measurable quantity that is used to describe the complete state of the system

Question 5

What is thermodynamic state of the system

Answer 5

Its defined by measurable macroscopic quantities called state variables or state properties

Question 6

How are state properties devided

Answer 6

1. Extensive-they depend on the system extension(amount of matter present in the system)(ex.:m,V,n, n=sum ni)
2. Intensive-dont depend on system extension and describe punctual properties of the system(p,ro,T,refractive index,dielectric constant)

Question 7

What gives ratio of 2 extensive properties

Answer 7

Intensive one

Question 8

Formula for pressure

Answer 8

p=F/S=ro×g×h, [Pa=N/m²=kg/ms²)

Question 9

Express following units
1bar=XPa
1atm=x bar=x Torr(mmHg)

Answer 9

1bar=10⁵Pa
1atm=1.01385 bar=760mmHg

Question 10

What is absolute temperature

Answer 10

Its measured on Kelvin
0°C=273.15K

Question 11

Give formula for how(from microscopic point of view) is T dependant on thermal motion of molecules/atoms

Answer 11

mv(x)²/2=k(B)T/2
kB=Boltzmans constant; kB=1.3×10^(-23)J/K

Question 12

What is state equation and give example of one

Answer 12

Relations that combine variables defining the system at equilibroum
p=f(V,T,n)

Question 13

What are independent and dependent state variables

Answer 13

•Independent state variable=set of state variables that uniquely determine the thermodynamic of the system
•Dependent state variable=expressed as a function of independent ones

Question 14

Ideal gas equation

Answer 14

pV=nRT

Question 15

What is pV also equal to

Answer 15

Energy
pV=force×displacement=energy

Question 16

Relation between R and kB

Answer 16

R=kB×NA

Question 17

What is Boyle’s law

Answer 17

The volume is inversly proportuonal to pressure
pi×Vi=pf×Vf

Question 18

What is Charles’s law

Answer 18

Volume is directly proportional to temperature
Vi/Ti=Vf/Tf

Question 19

What is Avogadro’s law

Answer 19

Equal volume of any ideal gas contains same number of moles if measured under same conditions(p and T)
Vi/ni=Vf/nf

Question 20

Do real gases abide by the ideal gas law

Answer 20

No, they deviate from it under high pressures because atom/molecules interact with each other through interactive forces

Question 21

What is compression factor

Answer 21

Z=pV/nRT
For ideal gasses Z=1
Z>1=happens because of attractive interactions between the molecules/atoms which causes number of hits pn the container to decrease
Z<1=those interactions are repulsive

Question 22

What are some state variables for liquids and solids

Answer 22

•because there are very small volume changes w pressure, we can consider V independent from p. We use molar volume
Vm=V/n=MM/ro
•at atm and room temp, Vm of liquids and solids is smaller than one of gases