Quiz 3: Chapter 4 Flashcards
What does Clausius say?
The entropy of an isolated system always increases in the course of a spontaneous process
What is the Clausius equation?
What is ΔGsys? What type is it? What type of equation is it? What is it best thought of as?
- ∆𝐺_sys is the change in Gibbs free energy.
- Gibbs free energy is not a “normal energy” because it is not conserved (if a spontaneous process occurs in the universe, the Gibbs free energy of the universe becomes more negative).
- The Gibbs equation is an “all-entropy” equation.
- ∆𝐺_sys is best thought of as the “dispersible amount of energy” or the “maximum non-pV work”.
How do you calculate the free energy change during the expansion/compression of a gas?
What is Q?
the reaction quotient
What is K?
the equilibrium quotient
Describe Q and K at equilibrium
At equilibrium ….
the partial pressures of the quotient Q correspond to the equilibrium partial pressures.
Therefore, Q = K and the Gibbs free energy is zero per definition ∆𝐺=0.
What is the standard gibbs free energy equation? What does this value represent?
Explain what the ratio of Q and K means for gibbs free energy.
What is one way Gibbs free energy can be interpreted?
Give an example of a partial molar quantity.
chemical potential
What is the best way to rationalize a partial molar property?
“the partial molar volume”
What is partial molar volume?
What does the partial molar volume depend on?
depends on how molecules pack in the liquid
Partial molar volume is ___________
- a derivative
- The partial molar volume of a substance A is the slope of the plot of the total volume as the amount of A is changed.
- The partial molar volume is not necessarily positive (addition of MgSO4 into water leads to a slight reduction of the total volume).
How do volumes of mixtures change? How can this change be calculated?
- the total volume of any mixture is the partial molar volumes at the composition of the mixture multiplied by the amounts.
What is chemical potential? What is the equation? What is the graph?
- The chemical potential of a substance A in a mixture is defined as the partial molar Gibbs energy
- The chemical potential is the contribution of that substance to the total Gibbs free energy
What is the fundamental equation of chemical thermodynamics? What happens to this equation under constant temperature and pressure?
- First two terms are dropped under constant T and P
What is 𝜉?
extent of reaction
What are the two interpretations of ∆𝑟𝐺?
- As a derivative and a difference
The free energy change for the reversible and isothermal expansion/compression of an ideal gas is:
Entirely entropic