enthalpy and entropy Flashcards
define entropy
a measure of the dispersal of energy in a system
when does entropy increase
when the system is more disordered
what is the symbol of entropy
S
solid or gas, which is more disordered?
gas
what are the units for standard entropy?
J K^-1 mol^-1
how does temperature affect entropy
the greater temperature particles have the more energy, and more movement
thus the arrangement of particles becomes more random
more random arrangement = higher entropy
when a solid ion lattice is dissolved in a solution what happens to the entropy
entropy increases because the ions are more disordered
how does a change in the number of gas molecules in a reaction affect entropy
increase in the number of gas molecules = increase in entropy
decrease in number of gas molecules = decrease in entropy
write the equation used to calculate the entropy change
entropy change = entropy of products = entropy of reactants
write the equation used to calculate the Gibbs free energy change and state what the symbols mean
∆G = ∆H - ∆(TS)
- ∆G - Gibbs free energy
- ∆H - enthalpy change
- ∆S - entropy change
- T - the temperature in Kelvin
enthalpy change = negative
entropy change = positive
what is the Gibbs free energy and the feasibility of the reaction?
Gibbs = always negative
feasible reaction
enthalpy change = positive
entropy change = negative
what is the Gibbs free energy and the feasibility of the reaction?
gibbs = always positive
reaction NEVER feasible
enthalpy change = positive
entropy change = positive
what is the Gibbs free energy and the feasibility of the reaction?
∆G = negative at low temperatures
feasible at low temperatures
enthalpy change = negative
entropy change = negative
what is the Gibbs free energy and the feasibility of the reaction?
∆G = negative at high temperatures
feasibility = feasible at high temperatures
for a reaction to occur spontaneously does ∆G must be positive or negative?
negative
