thermal physics (heat transfer, gas laws and kinetic theory)

Talk about the quick summary of the state of matter is so solid, liquid and gas

Solid is small and has strong lattice with strong forces of attraction and vibrate

Liquid, there are some gaps, less ordered, slow motion, flows easily

Gas out large gaps and no order therefore no forces of attraction and they are fast and move randomly

What is Internal energy mean and what is the equation for?

Why do molecules have Ek and Ep?

The sum of random distribution of kinetic and potential energies of the molecules in a system

U=sum of Ek + sum of Ep

Molecules have EK because of their motion and they have EP due to their position (Into molecular forces)

In an experiment to demonstrate brownie and motion in a gas, a brightly illuminated cell containing smoke is reviewed under a microscope. The observer can see a large number of bright specs undergoing random, jerky motions.what can you comment about this

The higher the temp, the faster the motion of the bright specks bc of more energy moving freely

An experiment was carried out to pressure of a fixed mass of gas varies with the temperature when it is in a volume 0.05 m³. The graph shows the y-axis to be the pressure and x-axis to be the temperature in kelvin with a gradient of 195.12. Calculate the no. of moles present

Use pV=nRt

Rearrange to make n the subject so n=pV/RT

Since p/T is the gradient technically, u use the gradient x volume all over the R constant to get the no. Of moles

What is thermal energy transfer? What are the three types?

Thermo energy transfer only occur if there is a temperature difference between the system and its surroundings. The three types are conduction, convection and radiation.

Explain the three types of thermal energy transfer

Conduction is where the energy transfer by lattice vibration and heat transfer in non-metallic crystals therefore free electrons move randomly in the lattice. This occurs in a solid and requires particles.

Convection is in a liquid and gas or any fluids and rise due to the temperature increase and falling due to colder more dense fluids. For example, hot molecules mean an increase in EK or molecules entering a colder fluid means an increase in average EK which equals a temperature rise

Radiation is the quantity and wavelength of radiation depending on the temperature

What is thermal equilibrium?

No net thermal transfer when system and this surroundings are the same temperature therefore two different temperatures will create an average EK for all molecules

What is considered an ideal gas?

No intermolecular forces therefore no EP

What is the first law of thermodynamics?

What is the equation and state an easier way to remember this?

An increase in internal energy is equal to the sum of energy transferred TO the system by heating/energy by work done ON it by external forces.

A decrease in internal energy is equal to the sum of energy transferred away from the system BY cooling/energy transferred AWAY from the system DOING work done AGAINST external forces

Change in U=+- change in WD +- change in Q (heat energy)

On=+wd (compressed)

By=-wd (expands or escapes)

Added to=+q (enters)

Given off=-q (leaves)

State the terms isothermal, isometric, isobaric, adiabaric

Takes place at the same temperature

Same value

Same pressure

Takes place so fast the change in Q = zero

How do you change Kelvin to degrees vice versa?

Kelvin=degrees+273

Degrees=kelvin-273

What are the equations can be used for Q?

Since Q is heat energy, this means any energy equations can be used

Ep=mgh

Ek=1/2mv²

Q=It=ne=eV

Q=Pt

How do you calculate the internal energy from the equation force equals pressure x area?

Force=wd

Change in Wd=pressure x area x difference in width

Change In Wd= pressure x volume

So the internal energy (U)=+-pV+-change in Q

What does specific heat capacity mean? And what is its equation and units?

Energy needed to raise the temperature of Unit mass 1 kg of material by one Kelvin

C=Q/(m x change in temp) or Q=m x c x change in temp

SHC. Measured in Jkg^-1K^-1

How do you calculate power using the specific heat capacity equation?

Q=m x c x change in temp

Q=Pt

P=(m x c x change in temp) over time

What is specific latent heat and what is its equation and units?

Thermal energy required to change the state of 1 kg without a change in temperature

L=Q/m

Jkg^-1

State and explain the two different ways to achieve specific latent heat (changing states)

Heat of fusion is the change from solid to liquid through melting or freezing

Heat of vaporisation is the change from a liquid to vapour through condensation or vaporisation

Explain Boyles law and its equation

For fixed mass of gas at a constant temperature, the volume is inversely proportional to the pressure

P1V1=P2V2

Explain the pressure temperature law/ amonton’s law and its equation

For fixed mass and volume of gas, the pressure is directly proportional to the absolute temperature of the gas

P1/T1=P2/T2

What is the definition for absolute zero?

The coolest temperature possible when the pressure is zero the molecule stop moving therefore 0EK

Explain Charles law and that equation

For fixed mass of gas at a constant pressure the volume is directly proportional to the absolute temperature

V1/T1=V2/T2

You can combine all the laws together what is the equation?

P1V1/T1= P2V2/T2

What is a mole?

Number of atoms in 12 g of carbon 12

What is the two equation to find the number of moles?

n=N/Na (molecule/avogadro constant)

n=m/M (mass of gas’s/molar mass)

Molar mass is the no. At the bottom of an element

What are the two equations for pV?

pV=NkT

pV=nRt

What were Brownian’s motion observations?

Smoke particles move randomly and continuously

Air molecules move randomly and continuously

Ammo must be smaller than the smoke particles and there must be a large number of molecules

What are the molecular theory assumptions?

Large number of molecules move randomly

Volume of gas molecules is negligible compared to volume occupied by gas

No intermolecular forces until collision

Collision between wall and molecules are elastic

Time of collision is negligible compared to the time between collisions

Between collision motion is in a straight line and a constant speed

What is the kinetic theory equation for one molecule and how do you use the kinetic theory equation using density?

pV=1/3 Nm (Crms)²

P=1/3 N x row x (Crms)²

How do you calculate the root means squared speed?

Square root ((s1)² +(s2)² so on) all over the no. Of speeds

How do you calculate the average EK?

Ek=1/2 m (Crms)²

Ek for 1 molecule= 3/2 kT

Ek for 1 mole= Ek for 1 molecule x Na

Ek for no. Of moles = 3/2 kT x (no of molecules) so n x Na

Ek= (3RT/2Na)

What does it mean when it ask for the internal energy?

Don’t forget the internal engine is just the sum of EK and EP so you use your equation for average EK to get the answer

How do you calculate the factor of Crms

Crms is directly proportional to square root of temp

Square root temp 1 over square root temp 2