CHEM 104 EXAMPREP REVIEW SHEET
WITH TESTED QUESTIONS AND COMPLETE
SOLUTIONS
●● What are the 4 important principles of equilibrium?
Answer: 1) All reactions eventually reach equilibrium
2) All species are present at equilibrium
3) Equilibrium is dynamic (though no observable changes)
4) Le Chatelier's principle - but will never return exactly to initial
equilibrium concentration
●● Define LeChatelier's principle
Answer: When a chemical system at equilibrium is disturbed, it returns
to equilibrium by counteracting disturbance
●● How do gases affect position of equilibrium?
Answer: Change in pressure of gas in the system will cause a shift
Addition of gas not in system has no effect
●● How does temperature affect equilibrium?
Answer: Temp = stress
, Heat considered a reactant in endothermic reactions and a product in
exothermic reactions
●● How do catalysts affect equilibrium?
Answer: They have no effect
●● How does the addition of a solvent (ex. water) affect equilibrium?
Answer: Causes a decrease in concentration of all aqueous solutions -
shifts to side with greatest amount of aqueous solutions
●● What is the equilibrium constant (Keq/Kc/Kp)?
Answer: - Products over reactants, raised to power of respective
coefficients in balanced chemical equation
- Has no units
- Solids and pure liquids not included
- Always positive, but can be large or small
●● What is the magnitude of Kc?
Answer: Measures yield of reaction at equilibrium
●● Describe the directionality of Kc
Answer: Kc > 1 = product-favored
Kc < 1 = reactant-favored
WITH TESTED QUESTIONS AND COMPLETE
SOLUTIONS
●● What are the 4 important principles of equilibrium?
Answer: 1) All reactions eventually reach equilibrium
2) All species are present at equilibrium
3) Equilibrium is dynamic (though no observable changes)
4) Le Chatelier's principle - but will never return exactly to initial
equilibrium concentration
●● Define LeChatelier's principle
Answer: When a chemical system at equilibrium is disturbed, it returns
to equilibrium by counteracting disturbance
●● How do gases affect position of equilibrium?
Answer: Change in pressure of gas in the system will cause a shift
Addition of gas not in system has no effect
●● How does temperature affect equilibrium?
Answer: Temp = stress
, Heat considered a reactant in endothermic reactions and a product in
exothermic reactions
●● How do catalysts affect equilibrium?
Answer: They have no effect
●● How does the addition of a solvent (ex. water) affect equilibrium?
Answer: Causes a decrease in concentration of all aqueous solutions -
shifts to side with greatest amount of aqueous solutions
●● What is the equilibrium constant (Keq/Kc/Kp)?
Answer: - Products over reactants, raised to power of respective
coefficients in balanced chemical equation
- Has no units
- Solids and pure liquids not included
- Always positive, but can be large or small
●● What is the magnitude of Kc?
Answer: Measures yield of reaction at equilibrium
●● Describe the directionality of Kc
Answer: Kc > 1 = product-favored
Kc < 1 = reactant-favored
