| Celsius to Fahrenheit | Fahrenheit to Celcius |
TF = (9/5)TC + 32  |
TC = 5/9(TF - 32) |
Temperature: is a relative measure or indication, of hotness or coldness.
Heat: is the net energy transferred from one object to another because of a temperature difference.
Once transferred, the energy becomes part of the total energy of the molecules of the object or system -- its internal energy.
When heat is transferred between two objects, whether or not they are touching, they are said to be in thermal contact.
When there is no longer a net heat transfer between objects in thermal contact, they have come to the same temperature and are said to be in thermal equilibrium.
A thermometer is a device constructed to make evident some property of a substance that changes with temperature.
The property most used to construct thermometers is thermal expansion.
| Celsius Temperature Scale |
Fahrenheit Temperature Scale |
|
| freezing point of water at 1 atm |
0°C | 32°F |
| boiling point of water at 1 atm |
100°C | 212°F |
| Celsius to Fahrenheit | Fahrenheit to Celcius |
| TF = (9/5)TC + 32 |
TC = 5/9(TF - 32) |
TK = TC + 273.15, Kelvin scale has the same interval as Celsius.
The Kelvin is based on Absolute Zero and the Triple Point of Water
Boyle's Law: pV = constant
Charles's Law: V/T = constant
Combined (ideal gas law): pV/T =
constant
pV/T = NkB, N = number of molecules, kB (Boltsman's constant) = 1.38 ´ 10-23 J/K, K is Kelvin Temperature.
pV = nRT, n = number of moles, R (universal gas
constant) = 8.31 J/(mol-K), T is in K.
A mole (mol) of a substance is defined as the quanity that contains Avogadro's number (NA) of molecules: NA = 6.02 ´ 1023 molecules/mol
The mass of 1 mole of any substance is simply its formula mass expressed in
grams.
The formula mass is determined from the chemical formula and the atomic masses of the atoms.
1 mole of any gas occupies 22.4 L at 0°C and 1 atm (standard temperature
and pressure).
| Linear | Area | Volume | |
| Solid | DL
= aLoDT
|
DA = 2aAoDT | DV = 3aVoDT |
| Liquid | DV
= bVoDT
|
a is the thermal coefficient of linear expansion.
b is the thermal coefficient of volume expansion.
water has the maximum density at 4˚C.
The Kelvin temperature is related directly to the internal energy of an ideal gas.
|
For monatomic and diatomic -- assuming that forces between molecules act only during collisions.
For monatomic gasses with no vibration or rotation:
|
This is a process of random molecular mixing in which particular molecules moved from a region where the are present in higher concentration to one where they are in lower concentration.
In general a lighter gas will be faster than a heavier gas at the same temperature. Therefore they will diffuse faster
It occurs in gases, in liquids and even to some degree in solids.
Effusion is dispersion through porous materials or permeable membranes.
The diffusion of liquid water across a permeable membrane down a concentration gradient is called osmosis.
How do we deal with diatomic gasses with the kinetic theory of gasses?
On average the total internal energy (U) of an ideal gas is divided equally among each degree of freedom its molecules possess. Furthermore, each degree of freedom contributes (1/2)NkBT or (1/2)nRT to the total energy.
A monatomic molecule has 3 degrees of freedom (x, y, z). In addition to this a diatomic molecule can also rotate round 2 different axis. Therefore a diatomic molecule has 5 degrees of freedom. Therefore the total energy is (5/2)nRT.