States of Matter

thermo

temperature

dynamics

changing

why do you need stats for thermodynamics?

because there are so many particles in systems, it makes more sense to use averages

0th Law of Thermo

A is same temp as B, B is same temp as C, so C is same temp as A

1st Law of Thermo

conversation of energy: system will not gain or lose heat energy unless another system provides an opportunity to

• heat is not spontaneously created

2nd Law of Thermo

entropy of isolated system always increases over time. as time passes hot things will naturally cool off

• heat always flows from larger to smaller temps

3rd Law of Thermo

you can never reach absolute zero, that would mean particles have no motion

absolute zero

the coldest possible temp

heat

energy being transferred, caused by particles in motion

temperature

measure of average kinetic energy of atoms

hand in water v hand hovering in oven

hand gets burnt in water because more particles in water (heat) but there is more temperature in the oven

Farenheit creator

Daniel Fahrenheit

Fahrenheit history

based on temperature of the body

• 100 thought to be temp of human body

• 0 is when human freezes to death

mostly all wrong

Celsius creator

Anders Celcius

Celsius history

originally determined on temps of water

• 100 boiling point of water

• 0 is freezing point for water

much more accurate

Kelvin creator

William Thompson aka Lord Kelvin

Kelvin history

originally determined on same scale as celsius

• 0 Celsius = 0K = absolute zero

entropy

measure of disorder or randomness, # of possible microstates in a macrostates

microstate

every possible arrangement of particles

macrostate

big picture description of what the system looks like

room cleaning entropy example

put things away on the shelves (ordered) but your room will keep getting messy (disordered)

entropy in thermo

hotter objects have larger concentration of energy, diffuses into its surroundings over time

• more possible micro states where energy isn’t as concentrated

states of matter

different states of matter behave differently and obey different equations of motion.

molecular motion

easiest way to tell states of matter apart by how it fills its volume

solid

definite shape and definite volume

• molecules tightly packed, unable to move freely, vibrate in place

liquid

definite volume, takes shape of its container

• molecules tightly packed, able to move freely, vibrate in various positions

Gas

no definite shape or volume, expands to fill container

• molecules are far apart, move in random directions with random velocities (larger velocity for hotter gases)

plasma

ionized gas (gasses with free electrons)

• very electronically conductive

4 fundamental states of matter

solid, liquid, gas, plasma

5 non-classical states of matter

glass, liquid crystal, etc

7 low temp

superfluid, bose-enstein, condenstate, etc

deionization

plasma → gas

ionization

gas → plasma

sublimation

solid → gas

deposition

gas → solid

melting

solid → liquid

freezing

liquid → solid

vaporization

liquid → gas

condensation

gas → liquid

why are there phase changes

temp or pressure

ideal gas

theoretical has that follows certain assumptions

• negligible intermolecular forces

• negligible particle volume

properties of an ideal gas

no volume

collisions elastic

no interaction between particles

example of an ideal gas

none, no real gas is actually ideal

• gases can act ideal under certain temperatures

Why do Balloons inflate

larger # of moles → moles bouncing off of each other → creates pressure → balloon expands

inflation

when pressure is larger than surrounding gas pressure

lungs inflating

diaphragm lowers → more volume → lower pressure → higher pressure around air from around lungs flows in → equalizes pressure difference

fluid

substance that can flow and continuously deform under application of force (liquids, gasses, other collections of small objects)

properties of fluids

1) density

2) viscosity

3) surface tension

4) compressibility

density

measure of how compact a substance is

• measured in kg/m³

• earth is arranged. by density

viscosity

resistance of a fluid to change shape or flow

• higher viscosity liquids flow slower

• can change viscosity with temp or composition

surface tension

property of the surface of a fluid that allows it to resist an external force

• due to cohesive nature of its molecules

• larger surface tension for denser fluids (why it only applies to liquids)

compressibility

measure of how much a fluid changes in volume when subjected to change in pressure

• gasses more compressible than all liquids

hydraulic systems

liquids incompressibility can be used to our advantage

• uses pressurized water

static

not moving or unchanging

fluid statics

study of fluids that don’t move

pressure

total force exerted over an area

pascal’s principle

pressure applied to an enclosed fluid is transmitted perfectly to all parts of fluid and its walls

buoyant force

upward force exerted on an object immersed in a fluid due to difference in pressure between top and bottom of the object

archimedes principle

buoyant force on an object is equal to the weight of the fluid displaced by the object

dynamic

moving or changing

fluid dynamics

applicable to fluids in motion

• dynamic properties only make sense when water is moving

flow continuity

for an incompressible fluid flowing through a pipe, the mass flow rate must remain constant

• if a river narrows, water must speed up to maintain same mass flowing past a certain point

Bernoulli’s Principle

as the velocity of a fluid increases, pressure decreases

laminar flow

fluid moves in parallel layers without mixing

turbulent flow

fluid undergoes irregular fluctuations, mixing