CHEM 104 Exam 2 (Latest
Update) | Questions and Verified
Answers | 100% Correct | A+
• Define chemical equilibrium -✓✓Forward and reverse reactions occur at equal rates
and concentrations of products and reactants remain constant (not necessarily equal)
• What are the 4 important principles of equilibrium? -✓✓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 -✓✓When a chemical system at equilibrium is disturbed,
it returns to equilibrium by counteracting disturbance
• How do gases affect position of equilibrium? -✓✓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? -✓✓Temp = stress
Heat considered a reactant in endothermic reactions and a product in exothermic
reactions
• How do catalysts affect equilibrium? -✓✓They have no effect
• How does the addition of a solvent (ex. water) affect equilibrium? -✓✓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)? -✓✓- 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? -✓✓Measures yield of reaction at equilibrium
• Describe the directionality of Kc -✓✓Kc > 1 = product-favored
Kc < 1 = reactant-favored
, • What is homogenous vs. heterogenous equilibrium? -✓✓Homogenous = all reactants
and products are present in single solution (homogenous mixture, same phase)
Heterogenous = reactants and products are in 2+ phases
• How can reactions and Kc be combined? -✓✓Flip reaction = inverse Kc (1/Kc)
Adding reactions = multiply Kc values
Multiple/divide by coefficient = raise Kc^n power
• What is the reaction quotient (Q)? -✓✓Represents sytem at any point in reaction; only
equals Keq when the reaction is at equilibrium
• What is the relationship between Keq & Q? -✓✓Q < K = shift right
Q > K = shift left
• Describe the steps to use an ICE table -✓✓1) Determine rxn direction to reach
equilibrium
2) Determine changes needed to reach equilibrium, then write equilibrium
concentrations in terms of changes (x = unknown magnitude of change)
3) Solve for x and equilibrium concentrations
4) Check arithmetic
• What is the shortcut/simplification to an ICE table? -✓✓If x is small (<5% initial
concentration), can be neglected
• What is the quadratic formula? -✓✓
• Define Arrhenius acid -✓✓Compound that dissolves in water to yield hydronium
(H3O+) ions
• Define Arrhenius base -✓✓Compound that dissolves in water to yield hydroxide (OH-)
ions
• Define Bronsted-Lowry acid -✓✓Compound that donates a proton to another
compound
• Define Bronsted-Lowry base -✓✓Compound that accepted a donated proton
• Define conjugate acid -✓✓The base molecule that has accepted a proton
• Define conjugate base -✓✓The acid molecule that has donated a proton
• Define amphiprotic -✓✓Species that may act as either an acid or a base, depending
on the conditions
Update) | Questions and Verified
Answers | 100% Correct | A+
• Define chemical equilibrium -✓✓Forward and reverse reactions occur at equal rates
and concentrations of products and reactants remain constant (not necessarily equal)
• What are the 4 important principles of equilibrium? -✓✓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 -✓✓When a chemical system at equilibrium is disturbed,
it returns to equilibrium by counteracting disturbance
• How do gases affect position of equilibrium? -✓✓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? -✓✓Temp = stress
Heat considered a reactant in endothermic reactions and a product in exothermic
reactions
• How do catalysts affect equilibrium? -✓✓They have no effect
• How does the addition of a solvent (ex. water) affect equilibrium? -✓✓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)? -✓✓- 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? -✓✓Measures yield of reaction at equilibrium
• Describe the directionality of Kc -✓✓Kc > 1 = product-favored
Kc < 1 = reactant-favored
, • What is homogenous vs. heterogenous equilibrium? -✓✓Homogenous = all reactants
and products are present in single solution (homogenous mixture, same phase)
Heterogenous = reactants and products are in 2+ phases
• How can reactions and Kc be combined? -✓✓Flip reaction = inverse Kc (1/Kc)
Adding reactions = multiply Kc values
Multiple/divide by coefficient = raise Kc^n power
• What is the reaction quotient (Q)? -✓✓Represents sytem at any point in reaction; only
equals Keq when the reaction is at equilibrium
• What is the relationship between Keq & Q? -✓✓Q < K = shift right
Q > K = shift left
• Describe the steps to use an ICE table -✓✓1) Determine rxn direction to reach
equilibrium
2) Determine changes needed to reach equilibrium, then write equilibrium
concentrations in terms of changes (x = unknown magnitude of change)
3) Solve for x and equilibrium concentrations
4) Check arithmetic
• What is the shortcut/simplification to an ICE table? -✓✓If x is small (<5% initial
concentration), can be neglected
• What is the quadratic formula? -✓✓
• Define Arrhenius acid -✓✓Compound that dissolves in water to yield hydronium
(H3O+) ions
• Define Arrhenius base -✓✓Compound that dissolves in water to yield hydroxide (OH-)
ions
• Define Bronsted-Lowry acid -✓✓Compound that donates a proton to another
compound
• Define Bronsted-Lowry base -✓✓Compound that accepted a donated proton
• Define conjugate acid -✓✓The base molecule that has accepted a proton
• Define conjugate base -✓✓The acid molecule that has donated a proton
• Define amphiprotic -✓✓Species that may act as either an acid or a base, depending
on the conditions
