Chapter 14 Temperature Flashcards
How does heat move from hot and cold objected
If object hotter than another, there is a net transfer of THERMAL energy from hot to cold until THERMAL equilibrium is reached
Thermal equilibrium is when there is no longer any net flow of thermal energy between them, thus SAME TEMPERATURE
Again what is thermal equilibrium
Thermal equkibkrum is when two objects have no net flow of thermal energy between them and thus at SAME TEMPERTAURE
What is zeroth law of thermodynamics?
If two objects are in thermal equilibrium with another, then all are actually in thermal equilibrium with each other
- could be useful
Why is it that thermometers can never hundred percent accurately measure temperature then
However why is it that measuring a human is correct
Because to measure temperature you want it to be the same temperature as the thing your measuring, however this won’t happen, as energy transfer will take place lowering the temperature if the surrounding that you wanted to measure in the first place!
2) negative feedback system whatever, energy always pumped out to ensure we correct tempertaure at all times so even if energy is taken it’s fine
Why do we touch things and think it’s cold? EVEN THO ITS SAME TEMP AS EVERYHTING ELSE
Heat transfer happens between hand and thing , and the more cold it is the greater rate if energy transfer and so especially for good conductors it feels even colder to touch EVEN THO ITS SAME TEMPERTAURE IS EVERYTHING ELSE AS IN THERMAL EQUILIBIRUM, but because rate of energy transfer is great feel fllld
What is the Kelvin scale formed on
Two points, absolute zero and triple point of water (where all three states at certain temp pressure aare in eaukibkrum )
But increments are the same as Celsius (so 1 increment)
Thus 273 increments from absolute 0 and triple point of water
Kinetic models of each state (3)?
Solid
- particles arranged in regular and arranged 3d structure
- string forces of attraction between the particles
- vibrate in fixed positions
Liquid
- particles free to move and take up shape of any container
- still forces of attraction
-
Gas
- negligible forces attraction between
Random motion
what is basic kinetic model that we try to prove using brownian motion
all matter made from particles
which have KE
what is Brownian Motion?
what is the velocities?
what is it a proof for and why?
1) its the random/ haphazard movement of particles suspended in a fluid (liquid/ gas) caused by collisons with surrounding fluid molecules.
2) this gives random velocities
3) Brownian Motion is a proof for the kinetic MODEL of matter, as it shows matter is made of particles, and that they have KE
how to observe brownian motion in the lab?
- use a smoke cell
-rthe smoke will scatter light and show against a dark background] - ## the jittery movements of the specks oflight are the smoke particles moving in random directions and random velocities due to colliding with ‘invisible’ water molecules
Density of things
Normally solid more dense except for water, thisnbevause hydorgen bonds hold them in fixed positions in an open lattice meaning average further apart than when liquid so less dense for same mass
What is INTERNAL ENERGY
Sum of randomly distributed kinetic and potential energies of atoms or molecules in a substance
What are examples of potential and kinetic
Kinetic jus kinetic energy, frim rotational or translational movement
But potential is due to electrostatic forces of attraction in intermolecular bonds
And the sum of this is internal energy
So explain graph of heating ice to a gas using internal energy ideas
TEMPERTAURE is just a measure of KINETIC energy. Thus heating will increase kinetic energy initially and thus internal energy.
However once they changing state, energy no longer increases TEMPERTAURE, however internal energy still increases!
- here energy is not kinetic so temp doesn’t increase. Here energy is transferred to POTENTIAL ENEEGY, so internal increase,
Only once phase changes will energy be transferred to kinetic again and temp revise
What are different potentials of different states. If you hear, are you inc or decreasinf the potential energy
How is a way to think about if something has high or low potential energy
Think of potential energy as jus energy transferred from surroundings to its form, so hotter = higher potential energy too and gases have highest potential at 0J, whereas solids have lowest potential
Or like potential is potential to make bonds. Solids have string bonds already so no pot Eileen
Potential is the ability to lose energy, we put a lot in gas, so it has most ability tomlose
Similar to chem, what happens when bonds re broken and what when bonds made
Bond breaking require energy bond making releases it, thus when water condensed it releases energy as bonds are made and in general potential energy decreases
What happens to internal energy if water as it condenses
What happens to temp of windo
Potential energy decrease as bonds are made, thus energy is releases. But as kinetic energy doesn’t change temp stays the same
However this potential energy is converted to kinetic and so the temperature of window increases!
So if blow on window it becomes war, for this reason
What has more internal water at 0 or ice at 0
Water, same temp so same ke but water has more potential so more internal
what is the internal energy at absolute 0 and the breakdowns of energies
0k = 0ke
however alwasy some potentinal energy ( going to infinity idea)
thus there is always some potential energy never 0 and thus internal energy is never 0 either!
what happens to internal energy and breakdown in energies as you heat something and it Changes state?
thus what happens to internal energy whenever you heat up no matter what is going on?
heating, temp increases so ke does, until you reach the melting point
at this point energy is no longer used to increase the ke of the particles, rather break the bonds
so as bonds are breaking, this means the POTENTIAL ENERGY is increasing! (thus internal too)
thus whenever you heat no matter what the internal energy will increase somehow
thus how will temp against time for constant power ( thus constant energy) graph look like
when will the temperature increase again?
as time increases energy total increases so ke does and temp too
however when it gets to CHANGING STATE, the graph will be horizontal, as now ke constant rather pe changing with time!
2) only after all particles have changed state will temp increase again
How do you explain that some water can evaporate below 100?
Use a Boltzmann distribution curve, some particles, very small amounts tho, will have enough energy that evaporate at even 0° but very few.
100 is jus temp at which ALL water evaporates !
Thus is why you spill water it will evaporate even tho room never hit 100
What is the triple point of water
At 0.1 , all three states exist in thermal equilibrium with each other, water ice and liquid , this is a point of comparison for the Kelvin scale
Again how can you think of potential and bonds
Potential to make bonds = high potential
Already got bonds, low potential
Potential energy to lose
What does the fact gases don’t have any potential energy mean about the volume they occupy at rip?
!!
volume at RTP is determined by the space between particles, and this varies due to having DIFFERENT BOND SIZE
However as gases have NO potential, they don’t have ANY bonds, thus one mole of gas at RTP will occupy the Sam’s volume NO MATTER THE GAS!
What is specific heat classify
Is the energy required per unit mass to change tempertaure by 1k
Water specific heat capacity
4.2g or 4200kg
So 4200j per kg of water to raise temp by 1k
Experiment for determining specific heat capacity and gradient analysis
How to make experiment better
Use an electric heater to heat up solid liquids and measure TEMPERTAURE against time.
Assuming all energy converted to thermal, VIT = MCaT
Rearrange to plot for temperature against time , and equate gradient to m and rearrange for c
Take means
In order to make better, ensure for insulation between heater and thing etc
How to use shc equatuins ti find new TEMPERTAURE if two mixtures or spherical heat capacity basically what assumption (when a hotter is added to colder)
1) obviously hotter become colder and colder hotter until they reach a certain TEMPERTAURE they they are in thermal equilibrium with
Assume that the energy left from the hotter is equal to energy gained by colder
Equate and solve
What’s wrong with the experiment before giving you higher answers of specific heat capacity
2 reasons + will c be higher or lower
1) as you start the thermistor doesn’t fear ckndtsnt heat so TEMPERTAURE readings slightly incorrect
2) as the solid increases TEMPERTAURE, it also increases RATE OF ENERGY TRANSFER SO LOSES ENERGY MORE, thus theoretically it will never be that high. This because change in temp properinsl to initial temp (differential )
- all this results in a lower gradient, which means a higher specific heat capacity then what ti should be!
REMMEBER about higher TEMPERTAURE substances compared to lower, what do they have higher
Yh higher TEMPERTAURE ones have higher rate of energy loss too
What is latent heat of a substance
The energy repaired ti raise unit mass to the next phase
Fusion is solid ti liquid and Vaporisation is liquid to gas
E=mL
Why is vaporisation higher reading then fusion, what’s going on with this energy (where on graph)
On the graph for phase change flat line represents increase in potential energy, and this is given by latent heat
Vap actually needs to break all the bonds so more energy needed, whereas fusion only needs to weaken them
Important about questions using latent heat
Say ice put in something, it will TAKE energy required it change its state from somewhere hotter, so work out change in temp of that first then work out how it becomes thermal equilibrium after
Latent heat is same temperature
How to work out fusion in experiment
Circuit with Hester snd substance, make sure substance ice is at correct temp, heat it and see the v I and the t used , energy electric = ml rearrange
How to work out specific latent vaporisation for water
Use condenser and same concept, electifcla heater and condense and then measure mass o how much was condensed in collecting, and current voltage and time and rearrange
REMMEBER about specific latent when turning into gas or back into solid
Back into solid means it release energy but into means it takes
Similar for shc
Remember that ICE AND WATEE HAVE
Different vs,use for SHC
Assume thst when something cools down what about power
Rate of energy lost constant so power constant
what happens to internal energy and breakdown in energies as you heat something and it Changes state?
thus what happens to internal energy whenever you heat up no matter what is going on?
heating, temp increases so ke does, until you reach the melting point
at this point energy is no longer used to increase the ke of the particles, rather break the bonds
so as bonds are breaking, this means the POTENTIAL ENERGY is increasing! (thus internal too)
thus whenever you heat no matter what the internal energy will increase somehow
