Thermal (Thermal Concepts) Flashcards
Define Temperature
an agreed upon standard to compare what is hot/cold
- proportional to the average kinetic energy of the atoms or molecules of the substance
- SI unit = kelvin (Absolute Temperature)
- international unit = Celcius
Kelvin = Celcuis + 273
What is “Absolute Zero”?
A theoretical point on the Kelvin scale where a substance’s atoms would have zero vibrational energy (It’s theoretical because atoms always have vibrational energy)
Define Heat
Transfer of thermal energy (Q)
*measured in Joules (J)
the energy that transfers from objects with higher temperature to objects with lower temperature that are in thermal contact.
NOTE: ONLY use these words when talking about the TRANSFER of energy
What is Thermal Equilibrium?
When objects are of the same temperature
*Heat will always flow until Thermal Equilibrium is reached
What is “Internal Energy”?
the sum of the total molecular random kinetic energy and potential energy in a substance
What happens when a substance gets heated?
- The molecules vibrate faster -> increasing Kinetic Energy
- The molecules move further apart -> increasing Potential Energy
- For solids, E(k) and E(p) are roughly the same amount
- in gases, the E(p) is almost negligible, almost all energy is E(k). (in an ideal gas, there’s NO E(p) between particles)
What is a “Specific Heat Capacity”?
Specific Heat Capacity (c)
The energy needed to increase the temp of a 1kg of a substance by 1K
* Measured in Joules per kg per kelvin (J)(kg^-1)(K^-1)
Why do some substances need different amounts of Thermal energy to heat up?
Some substances have stronger bonds and can store more potential energy before having to store energy as kinetic energy.
Meaning some substances need more energy to heat up in temperature
As energy is supplied to a substance, what happens when it changes phase (solid/liquid/gas)?
During a phase change, there is NO temperature change
*the energy is going to the bonds between the particles as E(p). so temp doesn’t change.
Define Latent Energy
Energy absorbed or released during a phase change
What is Specific Latent Heat
Amount of energy required for 1kg of a substance to change phase
*Measured in Joules per Kg (J)(kg^-1)
What do you call the Specific Latent Heat for Solid to liquid; liquid to gas; Solid to gas?
Solid to liquid = Fusion
Liquid to Gas = Vaporization
Solid to Gas = Sublimation
What are the intermolecular forces in a substance?
bonds holding molecules of a substance together through forces of attraction.
Strongest in Solids, weakest in Gases
What are the molecular properties of each phase?
Solid
- Volume is constant
- Shape is constant
Liquid
- Volume is constant
- Shape is variable (fits bottom of container)
Gas
* Volume is variable
* Shape is variable
(changes to fill its container)
