Lecture 3 Flashcards
What is a system?
A material with one or more phases
What is a phase?
Portion of the system whose properties are homogenous
What is a component?
Chemical element or compound which make up the system
What is composition?
Concentration of components in a phase
What is internal energy (U)?
includes both kinetic and potential energy?
What is enthalpy (H)?
The heat absorbed or released under constant pressure
What is entropy (S)?
A measure of the disorder of a system
What happens to Gibbs free energy (G) at constant pressure and temperature in a system at equilibrium?
Gibbs free energy (G) is at its minimum
What condition must be met for a spontaneous change to occur?
If the change in Gibbs free energy is negative.
What temperature is S zero for?
0 K
At what constants is the phase with lowest G the most stable?
At T and P
What does f stand for in Gibbs Phase Rule?
degrees of freedom
What does c stand for in Gibbs Phase Rule?
of components
What does p stand for in Gibbs Phase Rule?
of phases
What is special about the critical point in a phase diagram?
Where liquid and gas become indistinguishable. f=0
Does mixing 1L of water and 1L of alcohol result in exactly 2L of liquid?
No, 1+1 does not = 2. The final volume is less than 2L due to molecular interactions.
What kind of solution is the activity (ai) equals molar fraction (Xi)?
Ideal solution
What factors do not change after mixing?
Enthalpy and volume
