Thermal Physics Flashcards
what are volume, pressure and temperature
macroscopic (large-scale) properties.
if one is changed, at least one of the others will change.
they depend on how much gas is present, experiments must have a fixed gas
what is boyles law
(volume and pressure)
for a fixed mass of gas at constant temp, volume is inversely proportional to applied pressure
[pressure x volume= constant]
boyles law
why must oil have a low vapour pressure
oil content will change with pressure, in turn causing mass to change
boyles law
explain the use of the hand/foot pump
we very slowly inc pressure. compressing gas warms it slightly therefore after every compression wait a few moments for temp to dec
boyles law
what is isothermal
the same temperature
what is charles law
(volume and temperature)
for a fixed mass of gas at constant pressure, volume is directly proportional to Kelvin temp
[V/T=constant]
pressure law
why must water be stirred regularly
to ensure trapped air is same temp as water
charles law
what is the purpose of the concentrated sulfuric acid
traps and dries air to give better results
charles law
what is length y
a measure of volume of air
vol=πr² x h
charles law
what must water be stirred regularly
to ensure trapped air is same temp as water
charles law
what does a vol-temp(celcius) graph show
for a fixed mass of gas at constant pressure, volume increases uniformly with temp
what is the pressure law
(volume and temperature)
for a fixed mass of gas at constant volume, pressure is directly proportional to the kelvin temperature
[P/T=constant]
simple
state the ideal gas equation
pV/T=constant
p₁V₁/T₁ = p₂V₂/T₂
what is a mole
the amount of substance which contains as many particles as there are atoms in 0.012kg of carbon 12
avogadros number
6.02x10²³mol⁻1
what does avogadros number mean
the number of particles per mole
n=no. of molecules/avogadros no.
assumptions for kinetic theory
to define characteristics of an ideal gas
- no intermolecular forces (only when molecules collide)
- volume of molecules negligible to gas volume
- elastic collisions (moleucles and walls)
- time of collision negligible to time between collisions
- molecules have constant velocity (a=0)
moles
ideal gas equation
pV=nRT
pV=nRT
what is R
universal gas equation
8.31Jmol⁻1K⁻1
how to get boltzmann constant
k=R/avogadros number
boltzmann constant
1.38x10⁻23JK⁻1
what else is equal when p, V, T are equal
no. of molecules
mean square speed
ideal gas equation
pV=⅓Nmc²
boltzmann constant
ideal gas equation
pV=NkT
mean square speed
{c²}=c²+c²+c² ÷ N
<c²>
root mean square speed
c(rms)=√{c²}
density of gas
p=⅓ρ{c²}
speed and temp
kinetic energy
½m{c²}=NkT
kinetic energy directly proportional to Klevin temp
what is internal gas
the sum of potential and kinetic energy
what is the only energy monatomic gas possess ∴ ideal gases
translational kinetic energy
what is specific heat capacity
(c), the quantity of heat energy needed to raise the temp of 1kg of material by 1K
units J kg⁻1 K⁻1
specific heat capacity equation
Q=mcΔT
out of solid, liquid, gas what is the order of SHC
highest to lowest
gases>liquids>solids
SHC solid practical
what is the use of the small amount of oil in the hole with the thermometer
to improve thermal contactbetween thermometer and metal
SHC solid practical
what is the use of the metal being wrapped in insulator
to reduce heat loss, imporve accuracy
SHC solid practical
why must the experiment continue for several minutes after the heater is switched off
the temp of the heater is higher than the temp of block and takes time for equilibrium to be established
SHC liquid practical
what is the conatiner called that holds the liquid
calorimeter
SHC liquid practical
why must water be stirred throughout experiment
temp of liquid and temp of calorimeter must be the same
SHC liquid practical
ways to reduce error
- cool liquid in refridgerator to around 5° (liquid temp quickly rises until calorimeter and liquid are in equilibrium)
SHC liquid practical
describe when the heating starts and stops
- begins liquid and calorimeter are below 5° below room temp
- ends liquid is 5° above room temp
