week 1

Question 1

what is a system in thermodynamic

Answer 1

system is a universe defined by a boundary

Question 2

what is a boundary in thermodynamic

Answer 2

this can be an actual or imaginary limitation of an area

Question 3

what is a control volume in thermodynamic

Answer 3

if a boundary is fixed, then it is controlled via ‘control volume’

Question 4

what is a surrounding in thermodynamic

Answer 4

what is outside the actual system

Question 5

what are the types of systems called (2)

Answer 5

open and closed systems

Question 6

what is an open system?

Answer 6

one where mass many enter or leave the system (in this case at the same rate, not gathering more mass)

Question 7

what is the difference between gas constant and universal gas constant

Answer 7

gas constant is depending on the substance

the universal gas constant depends on nature

Question 8

what is the difference between gas constant and universal gas constant

Answer 8

gas constant is depending on the substance

the universal gas constant depends on nature (always constant)

Question 9

what is molar mass

Answer 9

this is mass of a given chemical element or compound divided by the amount of substance

Question 10

what is the equation for 1st law of thermodynamics (energy transfer into our out of system )

Answer 10

Q - W = (Change in) U

heat transfer - work done = change in internal energy

Question 11

how many independent parameters of state does air have

Answer 11

2 independent parameters
pressure and volume or pressure and temperature
temperature and volume and so on…..
different combinations but only 2 can be used to describe the air

Question 12

the equation to find the perfect gas

Answer 12

the equation of state:

pressure = desnity X gas constant X ABS temperature

Question 13

what is the value and units of universal gas constant

Answer 13

8.3J /mol K

Question 14

what is the gas constant of air

Answer 14

287 J/kg·K

Question 15

what does the air contain?

Answer 15

21% oxygen and 79% nitrogen

Question 16

what is the molar mass of air

Answer 16

28.97 g/mol

Question 17

what is entropy

Answer 17

measurement of disorder

measure of randomness or irreversibility of the system

Question 18

what does the first law show us

Answer 18

it shows us the energy balance equation:

Q - W = change in internal energy

Question 19

what does the second law show us (2)

Answer 19

entropy always increases or remains constant

thermal efficacy of any heat engine is always BELOW 100% (engine always produces heat)

Question 20

what does the second law show us (2)

Answer 20

entropy always increases or remains constant

thermal efficacy of any heat engine is always BELOW 100% (engine always produces heat)

Question 21

what does the third law show us

Answer 21

entropy is zero at zero temperature

Question 22

what does irreversibility mean, from the point of view of the behaviour of the system

Answer 22

entropy increases in irreversible processes

Question 23

how many processes does a cycle have

Answer 23

each cycle has 2 process as a minimum, mostly 4 but at least 2

Question 24

what thermodynamics processes are there (4)

Answer 24

adiabatic - no heat exchange
isobaric - pressure
isochoric - volume
isothermal - temperature

Question 25

isothermal

Answer 25

where the system’s temperature is constant

Question 26

isochoric

Answer 26

where the system’s volume is constant

Question 27

isobaric

Answer 27

where the system’s pressure is constant

Question 28

adiabatic

Answer 28

where no heat is exchanged by the system