Chapter 21 Thermal Physics and 22 Ideal Gases Flashcards
Internal energy
Sum of the random distribution of kinetic and potential energies of its atoms or molecules
Changing internal energy
Heating and compressing and passing a current through it, makes it bounce off faster and gain kinetic energy and temperature rises
First Law of Thermodynamics
Increase in internal energy = energy supplied by heating + energy supplied by doing work
First law of thermodynamics equation
U = q + w
Thermal energy
Hotter to cooler
Thermal equilibrium
Two objects of the same temp no transfer of energy
Thermodynamic Kelvin Scale
Absolute zero- min internal energy
Triple point- ice, liquid, vapor of water
Celsius to Kelvin
Theta+273.15
Thermometers
Resistance
Voltage
Volume of a fixed mass at constant pressure
Color of heated wire
Thermistor adv
Very robust
Fast response
Accurate
Sensitive at low temps
Thermocouple
Faster response Wider range Small thermal capacity Physically small, readings taken at a point Power supply not needed
Thermistor dis
Narrower range Slower response time Larger thermal capacity Larger in size Not suitable to measure varying temp
Thermocouple dis
For accurate reading, high resistance Voltmeter required
Melting and boiling
No change in temp
Temp is Ke
All energy used to break bonds
No change in ke no change in temp
Cooling effect of evaporation
Particles which escape are those with higher velocity so avg Ke of remaining decrease
Temp = avg Ke
Overall temp decreases
Kinetic theory of a gas
Molecules hit and rebound off walls
Change in momentum gives rise to force
Many impulses averaged to give constant force and pressure
Brownian motion: random motion of smoke particles
Ideal gas kinetic theory
Large number of particles
Negligible-
-intermolecular forces of attraction
-volume compared to container
Collisions perfectly elastic and no time spent
Avg Ke directly proportional to absolute zero
Boyle’s law and Charles law
Boyle’s: P € 1/V ; pV = k Charles’s: V € T; V/T = k P1V1/T1 = P2V2/T2
Ideal gas equation
PV = nRT
Specific latent heat
Is the energy required per kilo of the substance to change its state without any change in temperature
Specific latent heat equation
E = mL
L is slh
VIt = mL
Specific heat capacity
Energy required per unit mass of the substance to raise the temperature by 1k or 1°C
Pressure of molecules proof
Check book or revision guide
Temperature and molecular kinetic energy proof
Check book
Mean kinetic energy, mass and temperature
ke € T
ke € v^2
