Week 1- Thermodynamics Flashcards
What are the two sub-disciplines of thermodynamics?
Classical thermodynamics and statistical thermodynamics.
Describe classical thermodynamics:
Classical thermodynamics deals with bulks propertiens and consider the macroscopic properties of matter.
Describe statistical thermodynamics:
It also consider microscopic properties of matter and it refers to the probabilities of things happening at a molecular level.
What’s a system?
A system is anything contained within a boundary.
What are the 3 types of system?
1) Open system 2) Closed System 3) Isolated system
Describe open system:
Open system can exchange both energy and matter with the sorroundings
Describe closed system:
Closed system exchange only energy with the sorroundings.
Describe isolated system:
Isolated system cannot exchange either energy or matter with the sorroundings.
What’s sorrounding?
Sorrounding is everything else in contact with the system.
What’s energy?
Energy is the capacity to do a work.
What are the two types of energy?
1) Kinetic Energy 2) Potential Energy (Gravitational and chemical)
What’s potential chemical energy?
Energy stored in molecules by virtue of their bond.
What does bond formation do?
Bond formation release energy
What does bond breaking do?
Bond breaking consumes energy
What are the two ways by which energy can be transfered from the system to the sorrounding?
1)Heat 2) Work
What’s heat?
Heat is energy dispersed in a random motion
What’s work?
Work is energy dispersed as non random motion
Describe the -1 law of thermodynamics:
Heat travels from hot to cold
Describe the 0 law of thermodynamics:
If the body A is in thermal equilibrium with the body B and the body B is in thermal equilibrium with body C then the body A is in thermal equilibrium with the body C.
What’s internal energy?
Internal energy is the total energy within a system
Describe the 1st law of thermodynamics:
The internal energy of an isolated system is constant
What does Enthalphy measures?
Enthalpy measures the energy change in a system.
What’s energy change?
Energy change is the difference between the energy consumed by the breaking of bonds and the energy release by the formation of bonds.
If ΔH is negative…
If ΔH is negative the reaction is exothermic, system loses energy and become more stable.
If ΔH is positive…
If ΔH is positive the reaction is endothermic, the system acquire energy and become less stable.
What are the properties of spontaneus reactions?
Spontaneus reaction occurs without the input of energy and once started they proceeds to completion.
What is the property of non-spontaneus reactions?
Non-spontaneus reaction require energy to start and proceed.
What does Entrhopy measures?
Enthropy measures the ways in which energy is distributed within a system.
Describe the second law of thermodynamics:
The enthropy of an isolated system increase for any spontaneous change.
If ΔS is positive…
The reaction is spontaneous and exothermic.
What’s the tendency of ΔH?
ΔH tends to be negative due to the natural tendency to fall to lower energy state.
What’s the tendency of ΔS?
ΔS tends to be positive due to random thermal motion at molecular level.
What’s Gibbs free energy?
Gibbs free energy is the energy produced which is free to do work.
If ΔG is positive….
The reaction is non-spontaneous.
If ΔG is negative…
The reaction is spontaneous
If ΔG=0
The reaction is at thermal equilibrium
Describe the 3rd law of thermodynamics:
The entropy, S, of a perfect crystal at the absolute zero is 0.
What’s Boltzman probability?
Is the probability that the system will have an enthalphy H at a specific temperature T.
What is degenerancy?
Degenerancy (w) is the number of different way in which the system can adapt to the enthalpy.
Describe chemical equilibrium:
Chemical equilibrium is reached when the rate of the forward reaction is equal to the rate of the reverse reaction.
Describe dynamic equilibrium:
A dynamic equilibrium which can be described as the probability of molecule being at one state or another at any given time.
Describe heat capacity:
Heat capacity is the quantity of heat energy (q) we need to add to the system in order to increase its temperature.
