thurmal physics (everything) Flashcards
the higher the tempreture of a body the higher the…
avarge Ek of particals
what is the internal enegy of a body
Ek + potential enegy
what is a closed system…
this means that…
(need to be dubble checked)
a system wich does not allow transfer of enegy and mass in or out
total enegy is constent and there is no work done unless the body is heated or cooled
enegy is ______ ______ between particals within a system, through _______ ________ _______ but the _____ _______ ______ of all the particals ______ _____ duroing these collisions
constantly transfered, collisions between particals, total combined enegy, doesnt change
how can internal enegy be incresed
- by heating
OR - by doing work to transfer enegy to the system (e.g changing shape)
how can internal enegy be reduced
-by cooling
OR
-by doing work to remove enegy from the system
a change of state causes a…
internal enegy increases as a result of change in state:
- what changes to cause an increase in internal enegy
- what stays constent
this means…
change of potential energy
potential enegy of the particals is changed
while
Ek is constent
tempreture stays constent
specific heat capacity (c) is…
the amount of enegy needed to raise the tempreture of 1kg of a substanse by 1k (or1c’)
give enegy change equaition
(When dealing with c)
ΔQ=mcΔT
enegy change = mass x spesific heat capacity x change in tempreture
(Δθ or Δt is sometimes used intead of ΔT)
specific latent heat is…
therefore
the spesific latent heat (L) of _____ or ______ is the quantity of ______ ______ required to ______ ___ _____ of __ of a substance
the enegy needed to to brake the bonds that hold particals together therefore changing its state
(note you have to say some bonds if it is not a gass as there is still some bonds there)
fusion, vaoration, thurmal enegy, change the state, 1Kg
give the energy change equation
(for l)
ΔQ=ml
enegy change = mass of substance changed x specific latent heat
0K is where all particals have the _____ possible __
E of particals ∝
minumim, Ek
E of particals ∝tempreture
K (kelvin) =
K = C + 273
boyles law:
give equation
Explain
draw the graph
p∝1/V when T is constent
- if you reduce the volume of a gass the particals will be closer together
- therefore the particals will collid with each other and the container more often, so the pressure will increase
see pg 110
charles law:
equation
explain
draw the graph
V∝T when p is constent
- when you heat a gass the particals gain Ek.
- this means the particals move quicker and further apart
- therefore to keep constent pressure the gasses volume must increase
see pg 110
pressure law:
give equation
explain
draw graph
P∝T when V is constent
- if you increase the tempreture of a gass the particals within the gass will have a greater Ek
- this means the particals will move faster
- if volume is constent then the particals will collide with each other and the conainer more often
- thereofre increaseing the pressure
see pg 110
charles law, boyles law and the pressure law all apply if the gass is…
ideal
define temperature when dealing with gases
This is the measure of the average Ek of the particles
what does 1 mole contain
what is the mass of 1 mole of (4)(2)He
nomber of moles is represented as… and avagardos constent is represented as… and nomber of melecules is represented as…
therefore
nomber of molecules is given by the queation…
6.02x10^23 (avagardos constent N(A) - wich is number of atoms in a mole)
4g (1 mole is = to the reletive mass x 1g)
n, N(A), N
N=nN(A)
what is R and give its value
gas constent for 1 mole of gas
(8.31Jmol^-1K^-1)
give the ideal gas equation
when does this equation work well
pV=nRT
for when a real gass aproximats to a ideal gas.
this is when:
- low pressure
- high tempretures (compeared to there boiling point)
what is K (not kelvin)…
K also =
when does this work
gas constent for 1 partical
(1.38x10^-23JK^-1)
(boltzmanns constent)
K=R/N(A)
when dealing with large nombers of molecules
because K is a statistical avarge for 1 partical
give the equation of state equation
derive it
pV=NKT
pV=nRT
N=nN(A) K=R/N(A)
N/n=R/k
NK=nR
pV=NKT
work is done to change the _____ of gass at a constent ________.
this normaly involves transfer of….
give wd equations (not given)
draw graph of p/V, what is the area
volume, tempreture
heat
wd=pΔV
see pg 113, area=wd
give kenetic theory model equation
and dirive it
pV=1/3 x Nm(Crms)^2
see phone or pg 114
list all 5 assumption that are used in kinetic theory
what is the gas that obays these assumptions called?
- the molecules continually move about randomly
- the motion of the molecules follow Newton’s laws
- Collisions between molecules themselfs or at the walls of a container are perfectly elastic
- exept for during collisions, the molecules always move in stright lines
- any forces that act during collisions last for much less time than the time between collisions
an ideal gas
ideal gases have internal enegys that are dependent only on…
meaning…
kenetic enegy of the particals within the body
the potential enegy = 0J
when do real gases act like ideal gases
when:
- low pressure
- tempreture is high (compeared to there boiling point)
what is the 2 approximation for the kinetic enegy of the molecules in any substance equation
dirive both
Ek=3/2 x KT
Ek=3/2 x RT/N(A)
pV=1/3 x Nm(Crms)^2
pV= nRT
pV=pV
1/3 x Nm(Crms)^2 = nRT
1/2 x Nm(Crms)^2 = 2/3 x nRT
1/2 x m(Crms)^2 = 2/3 x nRT/N
NK = nR
1/2 x m(Crms)^2 = 2/3 x NkT/N
1/2 x m(Crms)^2 = 2/3 x kT
therefore Ek=2/3 x kT
K=R/N(A)
1/2 x m(Crms)^2 = 2/3 RT/N(A)
therefore Ek=2/3 RT/N(A)
emam question (2mark)
Tempreture is constent but pressure in oven decreases as atoms leave through an exit whole.
explain, using kinetic theory, why the pressure decreases
- because the nomber of particals within the oven decreases, the possible number of collisions per second also decreases.
- as the change in p experienced by a partical when colliding with the container is constent (u, speed is content)
then
the total Δp per second experienced by teh container will decrease
thereofre
presure drops
