Chemical Thermodynamics Flashcards
What does log10 mean (with example)?
How many times do we have to multiply 10 by itself to get our desired number
E.g. log10[100]= 2
as 10x10=100
What does ln mean?
Natural logarithm
Rather than log10, it is 10e, where e is Euler’s number
What is Euler’s number?
2.718
What is the reverse of ln(x)?
e^x
What are the 3 types of systems?
- Open system
- Closed system
- Isolated system
What is an open system?
System that allows transfer of mass and energy
What is a closed system?
Systems that allows transfer of heat, but not mass (e.g. sealed tube)
What is an isolated system?
System that does not allow transfer of mass or energy
What does kinetic energy come from?
Motion
What does potential energy come from?
Position of objects (e.g. position of atoms due to forces of attraction/repulsion)
What is the first law of thermodynamics?
The total energy of the Universe is constant.
Energy cannot be created or destroyed, only converted
What is a state function?
A property whose value does not depend on the path taken.
The value is independent of the path taken
What is a path function?
A property whose value does depend on the path taken to get from initial to final state
Examples of state function:
- Internal energy
- Entropy
- Gibbs
- Enthalpy
Examples of path function:
- Work done
- Heat transfer
What is the second law of thermodynamics?
Heat never flows spontaneously from a cold body to a hot body.
Any spontaneous change much be accompanied by an increase in the entropy of the Universe
What is important to remember when doing calculations involving energy and/or temp
Standard SI units:
Temp = Kelvin
Energy = Joules
What is latent heat?
During state changes, the temperature will cease to increase despite energy being put in.
This energy being put in, when you don’t see a change in temperature, is known as latent heat
Why does the temperature not increase for latent heat?
The energy is being used to push particles further apart
What is latent heat for solid to liquid known as?
Latent heat of fusion/melting
What is latent heat for liquid to gas known as?
Latent heat of vaporisation
What is the third law of thermodynamics?
The entropy of a pure crystalline substance at absolute zero is 0.
This represents a perfect crystal; nothing is in motion.
How can molar Gibbs energy be used as a measure of phase stability?
The most stable phase of a material always has the lowest molar energy
How does the state with the lowest molar Gibbs energy change as pressure increase?
As pressure increases, the state with the lowest molar Gibbs energy goes from:
gas -> liquid -> solid
What are standard conditions?
Temperature = 298K
Pressure = 1 atm
Concentration = 1 mol L-1
