Chapter 2A: Energy, Temperature & Heat Flashcards
(25 cards)
What is work?
Mechanical work is done when a force pushes, pulls or lifts matter.
What is internal energy?
Internal energy is the collective microscopic kinetic and potential energy of the molecules in a substance; it is a fundamental thermodynamic quantity.
What is radiant energy?
- Radiant energy is the energy associated with electromagnetic waves (photons).
- It is emitted by all bodies at temperatures above 0 K.
- RE = hc / λ
Define temperature
Temperature is a measure of the average kinetic energy of the atoms and molecules within a substance.
What happens at 0°C?
Water/ice melts
What happens at 100°C
Water boils (at sea level)
What is the absolute 0?
0 K is the absolute zero temperature. At this temperature, atomic motion (vibrations, rotations) are at a minimum (=no motion)
What is heat?
Heat is a form of energy in the process of being transferred from one object to another because of a difference in temperature.
(There is a transfer of heat until both objects have the same temperature)
What is the first law of thermodynamics?
- Heat is a form of energy
2. Energy is conserved
Statement of conservation of energy:
ΔQ= ΔU+ΔW
What are the variables?
ΔQ= the amount of heat added to a system (J) ΔU= change in internal energy ΔW= work done by the system on its surroundings
What is heat capacity?
Heat capacity is the ratio of the heat added to a substance to its corresponding rise in temperature.
What is specific heat capacity?
Specific heat capacity is the amount of heat (energy) required to raise the temperature of 1kg by 1°C.
Which is greater: specific heat capacity at constant pressure or specific heat capacity at constant volume?
Specific heat at constant PRESSURE is always greater than specific heat at constant volume. (cp=cv +R’)
Which has a higher specific heat capacity: water or air?
Water has a higher heat capacity. About 4x higher.
Water = 4186 J/kgK
Dry air = 1005 J/kgK (at constant pressure)
What does it mean that water has a higher specific heat capacity than air?
It means that water takes longer to heat up and longer to cool down.
→ Oceans take longer to heat up in the summer but are also slower to cool down in the winter (compared to heating/cooling of air)
What is sensible heat?
Sensible heat is the heat exchanged in a process associates with a change in temperature of the object.
→Formula: Qsens = CΔTm (C=specific heat capacity, either cp or cv depending on the process ; m=mass)
What is latent heat?
Latent heat is the energy required for a phase transition of a substance at constant temperature and volume.
QL= L*m where L is the latent heat of a specific phase transition
What is the phase change from solid to liquid?
Melting/Fusion
What is the phase change from liquid to solid?
Freezing
What is the phase change from liquid to vapour?
Evaporation/vaporization
What is the phase change from vapour to liquid?
Condensation
What is the phase change from solid to vapour?
Sublimation
What is the phase change from vapour to ice?
Deposition
Why is the release of heat due to the condensation of (liquid) water and the freezing of ice important to the atmosphere? (3)
- It drives cumulus cloud convection (release of energy in the cloud.
- It intensifies mid-latitude cyclones and hurricanes.
- It is an important driver for the global circulation (transport of water vapour followed by release of latent heat at different locations in the atmosphere)
