Thermal Physics Flashcards
What is Heat?
The spontaneous transfer of thermal energy, between two object caused by a difference in temperature.
What is the Symbol and Units of Heat?
Symbol: Q
Units: Joules
Why is heat transfered from one object to another?
because energy want sto be spread evenly and thus have energy spread equally between them
What is Temperature?
A measure of the average kinetic enrgy of the particles
What is the Symbol and Units of Temperature?
Symbol: θ or T
Units: K (for T) °C or K (for θ)
What is 0K in °C?
-273°C
What is Specific Heat Capacity?
The amount of energy required to change 1kg of material by 1K
What is the equation that links Heat and Specific Heat Capacity?
Q = mcΔθ Q = Thermal energy (heat) m = Mass c = Specific Heat Capacity Δθ = Change in temperature (K or °C)
What is the Units and Symbol for Specific Heat Capacity?
Symbol: c
Units: J/(kg x K)
What is Specific Latent Heat?
The amount of energy required to change the state of 1kg of a material, without changeing its temperature
What is the equation that links Specific Latent Heat and Heat?
Q = mL Q = Thermal Energy (heat) m = Mass L = Specific Latent Heat
What are the two types of Specific Latent Heat?
Specific Latent Heat of Fusion:
Solid ⇌ Liquid
Specific Latent Heat of Vaporisation:
Liquid ⇌ Gas
What is the Units and Symbol for Specific Latent Heat?
Symbol: L
Units: J/kg
What assumptions are made about ideal gasses?
Molecules are point masses.
Molecules move in random directions.
Collisions are elastic.
Time taken for collisions is negligable compared to time inbetween.
When does a real gas behave like an ideal gas?
When temperatures are high (incomparison to bp)
When pressure is low
What is an Ideal Gas?
A model used to explain the behavior of a gas
What is the equation for Pressure?
P = F/A P = Pressure F = Force A = Area
What is the Symbol and Units of Pressure?
Symbol: P
Units: N/m²
What affects the Pressure of a Gas?
Volume
Kinetic energy
Amount of Gas
Temperature
What are the Gas Laws?
They describe how Pressure, Temperature and Volume are related
What is Boyle’s Law?
pV = Constant
p ∝ 1/V
At a Constant Temperature
What is Charles’ Law?
V/T = Constant
V ∝ T
At a Constant Pressure
What is the Pressure Law?
p/T = Constant
p ∝ T
At a Constant Volume
What is the equation, when the three gas laws are combined?
pV/T = Constant
What are the two Ideal Gas Equations?
pV = nRT = NkT p = Pressure V = Volume n = number of moles R = gas constant N = Number of molecules k = Boltzmann constant T = Temperature
What is the Area of a Pressure-Volume graph?
Work Done
If a gas is compressed quickly what will happen?
It will increase in temperature to increase causing pressure to increase. Thermal energy cannot be lost to the surroundings fast enough
∴ both pressure and temp increase
If a gas a gas is compressed slowly what will happen?
It will increase in pressure.
It won’t increase in temperature as thermal energy is able to be lost to the surroundings
What assumptions are made by the Kinetic Theory of an Ideal Gas.
Molecules are point masses
Molecules have continuous random motion
No intermolecular forces
Collisions are elastic
What is the equation for the Kinetic Theory of an Ideal Gas?
pV = (1/3)Nm(Crms)² p = Pressure V = Volume N = Number of Molecules m = Mass of Molecule Crms = Root mean square speed of the molecules
How is an rms calculated?
Square all the values in the data set
Take a Mean of the square values
Root the Mean
What is the equation for the Average Molecular Kinetic Energy?
E = 0.5m(Crms)² = 1.5kT = 3RT/2N E = Energy m = Mass Crms Root mean square speed k = Boltzmann Constant T = Temperature R = Gas Constant N = Number of Molecules
