Chemical Equilibrium and Constants Quiz

Chemical Equilibrium

• Chemical equilibrium is a state where the forward and reverse reactions occur at equal rates.
• The concentrations of reactants and products become constant, meaning no further net change in concentrations.
• This occurs when the rate of the forward reaction equals the rate of the reverse reaction.

Equilibrium Constant(Kc)

• Equilibrium constant expression: Kc = [products]/[reactants], where the exponents are the stoichiometric coefficients of the balanced reaction equation.
• Equilibrium constant values help determine the extent of reaction and prediction of the direction of a reaction.
• The larger the value of Kc, the further the reaction proceeds to form products before reaching equilibrium.
• A very small Kc means the reaction proceeds hardly at all, mostly reactants and their concentrations remain high.

Reaction Quotient(Qc)

• Reaction quotient is a similar calculation to Kc, but it is calculated at any point during the reaction, not just at equilibrium.
• If Qc < Kc, the reaction will proceed forward, favoring product formation
• If Qc > Kc, the reaction will proceed in the reverse direction, favoring reactant formation
• If Qc = Kc, the reaction is at equilibrium.

Factors Affecting Equilibrium

• Concentration: Adding more reactants or products shifts the equilibrium in the direction that consumes the added substance. Removing reactants or products shifts the equilibrium in the direction that generates the removed substance.
• Pressure and Volume: Increasing pressure/decreasing volume favors the side with fewer moles of gas. Conversely, decreasing pressure/increasing volume shifts the equilibrium towards the side with more moles of gas.
• Temperature: Endothermic reactions (positive ∆H°) shift to the right (products side) as temperature increases. Exothermic reactions (negative ∆H°) shift to the left (reactants side) as temperature increases.

Catalysts

• Catalysts speed up both forward and reverse reactions equally. This does not affect the equilibrium composition of the reaction mixture.

Le Chatelier's Principle

• If a change (stress) is applied to a system at equilibrium, the system shifts in a direction to relieve the stress.

Solubility Equilibria

• The solubility product constant (Ksp) describes the equilibrium between a solid ionic compound and its dissolved ions in a saturated solution.
• Adding a common ion to a solution reduces solubility of the solid compound.

Solubility and pH of the Solution

• Solubility of ionic compounds containing basic anions increases with increasing acidity of the solution.
• Salts with anions of strong acids are unaffected by pH changes.

Solubility and Complex Ions

• Solubility of ionic compounds increases dramatically if the solution contains a Lewis base that can coordinate with the metal cation.
• This forms complex ions, thus shifting the equilibrium to favor the dissolved state

Test your understanding of chemical equilibrium, equilibrium constants, and reaction quotients. This quiz covers key concepts like Kc, Qc, and the implications of their values in chemical reactions. Perfect for chemistry students looking to solidify their knowledge on equilibrium dynamics.