Chp 2: Thermodynamics Flashcards
Describe the kinetic particle model.
It states that the small particles that make up all matter have kinetic energy, thus, all particles are in constant motion.
What is the difference between thermal energy, heat and temperature?
Thermal energy is the energy a substance has because of its temperature.
Heat is the transfer of thermal energy from a hotter to colder body.
Temperature is related to the average kinetic energy of the particles in a substance.
What is the different between kinetic and internal energy?
Kinetic energy is the energy of movement, it’s equal to the amount of work needed to bring an object from rest to motion
Internal energy is the total kinetic and potential energy of the particles within a substance
Outline conduction, convection and radiation
Conduction - heat transfer without the net movement of particles. can occur within a material or between materials in thermal contact
Convection - heat transfer within a fluid by movement of hot areas from one place to another. there is mass movement of particles
Radiation - thermal energy transfer via electromagnetic waves. the radiation falls on an object, it can be reflected, transmitted and absorbed
How do you convert temperature between Celsius and Kelvin?
Kelvin = Celsius + 273
What causes a change in temperature?
an addition or removal of energy from a system without phase change occuring
Define specific heat capacity
defined as ‘c’ - It’s the amount of energy that must be transferred to change the temperature of a 1kg mass by 1°C or 1K
Q = mcΔT
Why does the temperature of a substance not increase/decrease during phase change?
The energy within the particles goes into breaking down the bonds in the substance for phase change instead of increasing the temperature
Define specific latent heat
It’s the energy required to change the state of 1 kg of material to a constant temperature
What is the difference between latent heat of fusion and latent heat of vaporization?
Fusion - when a substance/object is melting eg. from solid to liquid OR liquid to solid when cooling
Vaporization - when a substance/object is boiling eg. liquid to gas OR gas to liquid
Define thermal equilibrium
If two objects are in thermal contact, thermal energy will flow from one hot object to the cold object until two objects are at the same temperature
Explain the zeroth law of thermodynamics
If A and B are the same temp as C, A and B are the same temp. heat cannot be created nor destroyed meaning thermal energy lost by one substance is gained by another
Use Qlost = Qgained
Thermal energy relation to mechanical work
Thermal energy has the capacity to do mechanical work. This is calculated using ΔU = Q-W
Heating = +Q, cooling = -Q
Work done ON = -W Work done BY = +W
What is the first law of thermodynamics
It states that energy simply changes from one form to another and the total energy in a system is constant. This is a consequence of the law of conservation of energy.
Define efficiency in relation to energy
It is a comparison of the energy output to the energy input in a given system. Given as a percentage %
