2.1-2.4 Flashcards
How do you know if the entropy change is +
-Solid into a liquid
-If gas molecules increased from reactants to products
How do you know if an entropy change is -
-Gas to liquid or liquid to solid
-If g molecules dec.
A rxn is enthalpy driven if ___
Change of enthalpy is - (exo, -kJ, heat on product side)
A rxn is entropy driven if ___
If change of entropy is +
What is an “open system”
-Allow some/all products to escape
-Not available for reverse rxn (open flask)
What is a “closed system”
-Will not allow products to escape
-eg Closed flask
How to recognize a rxn in equilibrium
-Closed system
-Opposite rxn’s occur at same rate
-Can reach equil. starting with reactants or products
-Observe no visible chem. changes
-Temp at equil. is constant
Which side is favoured. Side of reaction having least (min. energy/exo) or most (max. energy/endo) enthalpy
Least
What are the 2 “tendencies” of reactions
-Tendency to go to side with min. enthalpy
-Tendency to go to side with max. entropy
Which phases have the most entropy (most to least)
G, aq, l, s
Does the side having the least or most molecules have the most entropy
Most
If min. enthalpy favors reactant side, and max. entropy favors product side, overall the rxn will
Form an equil.
If both min. enthalpy and max. entropy favors reactant side, overall the rxn will
Go in reverse only
If both min. enthalpy and max. entropy favors product side, overall the rxn will
Go forward only
If heat is added, shift will be left or right
-Right if heat is on reactant side (to remove heat)
-Left if heat is on product side (to add heat)
If we inc. pressure we dec. volume, so equil. will shift to side of rxn having the most or least moles of g present
Least
How to decide if shift will be left or right depending on inc. or. dec. of conc.
-RIGHT if species is inc. and on reactant side OR species conc. is dec. and on product side
-LEFT if species is dec. and on reactant side OR species conc. is inc. and on product side
-Essentially, inc. = move towards equil. arrows, dec. = move away from equil. arrows
What happens to equil. when catalyst is added
No change
Changing amount of s or L reactants or products in a rxn in equil, will NOT affect equil. T or F
True
How to know if reaction is enthalpy driven
Delta H term is -
How to know if reaction is entropy driven
Delat S term is +
