Q: How does Le Chatelier's principle work?

Le Chatelier's principle states that when a system at equilibrium is disturbed, it shifts to counteract the disturbance. If a reactant concentration is increased, the system shifts toward products. If temperature is raised for an exothermic reaction (ΔH < 0), the equilibrium shifts toward reactants (Kc decreases). Increased pressure shifts equilibrium toward the side with fewer moles of gas.

Q: How is the ICE table method used?

The ICE (Initial, Change, Equilibrium) table method tracks concentration changes. Set initial concentrations, express changes as ±nx where n is the stoichiometric coefficient, substitute equilibrium expressions into the Kc formula, and solve for x. This tool uses bisection to solve the resulting polynomial equation numerically.

Q: What is the Van't Hoff equation used for?

The Van't Hoff equation d(ln K)/dT = ΔH°/(RT²) describes how the equilibrium constant changes with temperature. In integrated form: ln(K₂/K₁) = -ΔH°/R × (1/T₂ - 1/T₁). For exothermic reactions (ΔH° 0), Kc increases with temperature.

Question 1

What is the equilibrium constant Kc?

Accepted Answer

The equilibrium constant Kc is defined as the ratio of product concentrations to reactant concentrations, each raised to the power of their stoichiometric coefficients, at equilibrium. For aA + bB ⇌ cC + dD: Kc = [C]^c[D]^d / ([A]^a[B]^b). A large Kc (>>1) means the equilibrium favors products; a small Kc (<<1) means it favors reactants. Kc depends only on temperature.

Question 2

How does Le Chatelier's principle work?

Accepted Answer

Le Chatelier's principle states that when a system at equilibrium is disturbed, it shifts to counteract the disturbance. If a reactant concentration is increased, the system shifts toward products. If temperature is raised for an exothermic reaction (ΔH < 0), the equilibrium shifts toward reactants (Kc decreases). Increased pressure shifts equilibrium toward the side with fewer moles of gas.

Question 3

How is the ICE table method used?

Accepted Answer

The ICE (Initial, Change, Equilibrium) table method tracks concentration changes. Set initial concentrations, express changes as ±nx where n is the stoichiometric coefficient, substitute equilibrium expressions into the Kc formula, and solve for x. This tool uses bisection to solve the resulting polynomial equation numerically.

Question 4

What is the Van't Hoff equation used for?

Accepted Answer

The Van't Hoff equation d(ln K)/dT = ΔH°/(RT²) describes how the equilibrium constant changes with temperature. In integrated form: ln(K₂/K₁) = -ΔH°/R × (1/T₂ - 1/T₁). For exothermic reactions (ΔH° < 0), Kc decreases with increasing temperature. For endothermic reactions (ΔH° > 0), Kc increases with temperature.

Chemical Equilibrium · Le Chatelier's Principle

Theory