Module 5 Flashcards
What is thermal equilibrium?
When two substances in physical contact with eachother no longer exchange any heat energy and both reach an equal temperature
Why do we use Kelvin instead of Celsius?
Celsius is based on the properties of water meaning it’s not arbitrary. The freezing and boiling points of water can change as it’s pressure changes.
Characteristics of a solid?
Particle arrangement: fixed structure
Space between particles: no space
Intermolecular forces: strong
Particle movement: vibrate around a fixed position
Particle energy: low
Substance shape: fixed
Substance volume: high
Characteristics of a liquid?
Particle arrangement: random
Space between particles: some space
Intermolecular forces: weak
Particle movement: flow past each other
Particle energy: medium
Substance shape: not fixed
Substance volume: fixed
Substance density: medium
Characteristics of a gas?
Fixed pattern: random
Space between particles: large space
Intermolecular forces: negligible
Particle movement: move around at different speeds
Particle energy: high
Substance shape: not fixed
Substance density: low
What is Brownian motion?
Small particles (such as pollen or smoke particles) suspended in a liquid or gas are observed to move around in a constant, random motion
Why do particles change their speed and direction randomly?
Collisions
The smaller particles can affect the larger particles this way because they are travelling at a speed much higher than the larger particles
They have a lot of momentum which they transfer to the larger particles when they collide.
What is internal energy?
The sum of randomly distributed kinetic and potential energies of atoms or molecules within a substance
What is kinetic energy?
Energy due to an objects motion
What is potential energy?
Energy due to the separation between the molecules and their position within the structuren
How does temperature affect the internal energy of an object?
Higher temperature means greater kinetic energy
How do intermolecular forces affect internal energy?
Stronger intermolecular forces mean higher potential energy
How is internal energy lost?
Gas -> liquid or liquid -> solid
Losing heat to the surroundings
What is absolute zero? (Temperature scale)
The lowest temperature possible. Equal to 0K or -273.15 C
What is the definition of absolute zero?
The temperature at which the molecules in a substance have zero kinetic energy
Definition of specific heat capacity?
The amount of thermal energy required to raise the temperature of 1kg of a substance by 1C
Characteristics of a substance with low heat capacity?
Heats up and cools down quickly
E=mcΔθ?
E = thermal energy
m = mass of the substance
c = specific heat capacity of the substance
θ = change in temperature
Definition of latent heat?
Thermal energy required to change the state of 1kg of mass of a substance without any change in temperature
What are the two types of latent heat?
Latent heat of fusion (melting)
Latent heat of vaporisation (boiling)
How do we determine specific latent heat?
E = mL
E = thermal energy to change state
L = heat of fusion or vaporisation
m = mass of the substance
Definition of the mole?
The SI abase unit of an amount of substance. It is the amount containing as many particles as there are atoms of 12g of carbon -12
Definition of avogadros constant?
The number of atoms of carbon -12 in 12g of carbon -12 equal to 6.02x10^23 mol
How do we calculate molar mass?
Number of moles = mass/molar mass
Unit of molar mass = g mol-1
What is an ideal gas?
Gas which has negligible volume
Collisions which are elastic
Cannot be liquified
Has no interaction between the molecules
Obeys the ideal gas laws
Ideal gas equation?
pV = nRT or pV = NkT
P= pressure
V = volume
n = number of moles
R = molar gas constant
T = temperature
N = number of molecules
K = Boltzmanns constant
What is boyles law?
Pressure is inversely proportional to the volume of gas
- pressure increases when the gas is compressed
p1v1 =p2v2
What is the pressure law?
Pressure is proportional to temperature
P1/T1 = P2/T2
What is Charles law?
Estimating absolute zero
Volume is proportional to temperature
V1/T1 = V2/T2
Kinetic theory of gases, Newton’s second law equation?
- F = Δρ/Δt = - 2mv/Δt
Describe kinetic theory of gases for a particle hitting the wall?
A particle hitting the wall of a container in the gas is held experienced a force from the wall and a change in momentum. The particles exerts an equal and opposite force on the wall
Kinetic theory of gases equation?
pV = 1/3N m c2
p = pressure
V = volume
N = number of molecules
m = mass of one molecule of gas
C2 = mean square speed of the molecules
Kinetic theory of gases density equation?
density = mass/volume = Nm/V
p = 1/3 ρ c 2
P = pressure
ρ = density
c2 = mean square speed of the molecules
Rearrange for average kinetic energy of a particle?
pV =1/3 Nmc2
1/3Nmc2 = Nkt
1/3 mc2 = kT
mc2 = 3kT
2E = mc2 = 3KT
E = 1/2 mc2 = 3/2kT
How do we convert from degrees to radians?
θ x pi/180 = θrad
How to we convert from radians to pi?
θrad x 180/pi = θ
How do we calculate angular displacement?
θ = s/r
Length of arc = s
Radius = r
Definition of frequency?
The number of complete oscillations per unit time
Define time period
Time taken for one complete oscillation in seconds
Define one oscillation?
Time taken for the oscillation to pass the equilibrium from one side and back again fully from the other side
How do we calculate speed of an object in a circle?
Speed = distance/ time
So
Distance = 2 x pi x radius
Time = time period
Define angular displacement?
Change in angle, in radians, of a body as it rotates around a circle
Newton’s first law definition?
A body will remain at rest or on the move with constant velocity unless acted on by a resultant force
Define Newton’s second law
The resultant force on an object is equal to its rate of change in momentum
Define Newton’s third law?
If body A exerts a force on body B, then body B will exert a force on body A of equal magnitude but in the opposite direction.
Examples of centripetal force?
Car travelling around a roundabout = friction between car tires and the road
Ball attached to a rope moving in a circle = tension in the rope
Earth orbiting the sub = gravitational force
Define centripetal force?
The resultant force towards the centre of a circle required to keep a body in uniform circular motion
Equation for linear speed?
v = rω
V = linear speed
r = radius
ω = angular speed
Definition for centripetal acceleration?
Acceleration of an object towards the centre of a circle when an object is rotating around a circle at constant speed
Equations for centripetal acceleration?
a = v2/r
a = (rω)2 / r
a = rω2
a = ωv
Equation for angular frequency?
ω = 2 pi/ t = 2 pi f
Conditions of simple harmonic motion?
Acceleration of a body is proportional to its displacement but acts in the opposite direction
