Le Châtelier’s Principle Flashcards

A set of vocabulary flashcards based on the lecture and lab manual for Le Châtelier’s Principle and chemical equilibrium systems.

Reversible Reaction

A reaction in which both the conversion of reactants to products (forward reaction) and the re-conversion of products to reactants (backward reaction) occur simultaneously.

Chemical Equilibrium

A dynamic state in a reversible reaction where the rate of the forward reaction is equal to the rate of the backward reaction, and the concentrations of reactants and products remain constant.

Le Châtelier’s Principle

If a stress is applied to a reversible reaction at equilibrium, the reaction will undergo a shift to re-establish its equilibrium.

Stress

A disturbance applied to an equilibrium system, such as increasing or decreasing chemical concentrations or changing the temperature.

Exothermic Reaction

A reaction where heat energy is released and can be considered a product, represented as $A + B \rightleftharpoons C + D + \text{heat}$.

Endothermic Reaction

A reaction where heat energy is absorbed and can be considered a reactant, represented as $A + B + \text{heat} \rightleftharpoons C + D$.

Shift to the Right

Occurs when the net forward reaction increases to reduce added reactants or replace removed products.

Shift to the Left

Occurs when the net backward reaction increases to reduce added products or replace removed reactants.

Acidified Chromate Equilibrium

The reversible system between yellow chromate and orange dichromate: $2 CrO_4^{2-} (aq) + 2 H^+ (aq) \rightleftharpoons Cr_2O_7^{2-} (aq) + H_2O (l)$.

Aqueous Ammonia Equilibrium

The system involving ammonia and phenolphthalein: $NH_3 (aq) + H_2O (l) \rightleftharpoons NH_4^+ (aq) + OH^- (aq)$, where pink color indicates presence of $OH^-$.

Cobalt(II) Chloride Equilibrium

The system between pink and blue complexes: $Co(H_2O)_6^{2+} (aq) + 4 Cl^- (aq) \rightleftharpoons CoCl_4^{2-} (aq) + 6 H_2O (l)$.

Iron(III) Thiocyanate Equilibrium

The system involving yellow $Fe^{3+} (aq)$, colorless $SCN^- (aq)$, and deep red $Fe(SCN)^{2+} (aq)$.

Neutralization Reaction

The process where hydroxide ions remove acidic hydrogen ions from a system: $H^+ (aq) + OH^- (aq) \rightarrow H_2O (l)$.

Precipitation Reaction

The process where ions combine to form a solid, such as silver nitrate removing thiocyanate: $Ag^+ (aq) + SCN^- (aq) \rightarrow AgSCN (s)$.