Factors Affecting Chemical Equilibrium

Front

Le Châtelier's Principle Noun

---

[luh shah-tuh-lyeyz prin-suh-puhl]

Back

Le Châtelier's Principle

---

A principle stating that if a stress is applied to a system at equilibrium, the system shifts to relieve it.

---

Example: This diagram shows that when a balanced chemical reaction is disturbed (by adding reactants, or changing pressure or temperature), the system will shift to counteract that change and find a new balance.

Front

Stress (Chemical Equilibrium) Noun

---

[stres]

Back

Stress (Chemical Equilibrium)

---

Any change in concentration, temperature, volume, or pressure that disrupts a system at equilibrium and causes a shift.

---

Example: This analogy shows that when a "stress" (like adding more water) is applied to a system at equilibrium, the system shifts to counteract the stress and establish a new equilibrium.

Front

Equilibrium Position Noun

---

[ee-kwuh-lib-ree-uhm puh-zish-uhn]

Back

Equilibrium Position

---

The relative concentrations of reactants and products in a reaction at equilibrium, which can shift in response to stress.

---

Example: This image shows a hand pushing down on a balance scale, representing how an external factor or "stress" can shift the equilibrium position of a system.

Front

Equilibrium Constant (Keq) Noun

---

[ee-kwuh-lib-ree-uhm kon-stuhnt]

Back

Equilibrium Constant (Keq)

---

The ratio of product concentrations to reactant concentrations at equilibrium, with each raised to its stoichiometric coefficient's power.

---

Example: A balanced scale represents chemical equilibrium, the state where the ratio of products to reactants is constant (Keq).

Front

Concentration Noun

---

[kon-suhn-trey-shuhn]

Back

Concentration

---

The amount of a substance present in a defined space, typically expressed as moles per liter for chemical solutions.

---

Example: Adding dye to water creates a high concentration area; the dye particles then spread out until they are evenly distributed, reaching a state of equilibrium.

Front

Forward Reaction Noun

---

[fawr-werd ree-ak-shuhn]

Back

Forward Reaction

---

In a reversible reaction, the process that converts reactants into products, typically shown proceeding from left to right.

---

Example: This image shows reactants (CH₄ and O₂) on the left turning into products (CO₂ and H₂O) on the right, indicated by the single forward arrow.

Front

Reverse Reaction Noun

---

[ri-vurs ree-ak-shuhn]

Back

Reverse Reaction

---

In a reversible reaction, the process that converts products back into reactants, typically shown proceeding from right to left.

---

Example: This diagram shows that reactants A and B can form products C and D, and simultaneously, products C and D can react to re-form reactants A and B.

Front

Exothermic Reaction Noun

---

[ek-soh-thur-mik ree-ak-shuhn]

Back

Exothermic Reaction

---

A chemical reaction that releases energy into its surroundings, often as heat, and has a negative enthalpy change (ΔH).

---

Example: An exothermic reaction releases heat energy into its surroundings, causing the temperature of the container and its environment to increase.

Front

Endothermic Reaction Noun

---

[en-doh-thur-mik ree-ak-shuhn]

Back

Endothermic Reaction

---

A chemical reaction that absorbs energy from its surroundings, often as heat, and has a positive enthalpy change (ΔH).

---

Example: This diagram shows that an endothermic reaction needs to absorb heat energy from its surroundings to turn reactants into products.

Front

Catalyst Noun

---

[kat-l-ist]

Back

Catalyst

---

A substance that increases a reaction's rate by lowering activation energy without being consumed or changing the equilibrium position.

---

Example: A catalytic converter uses a catalyst to speed up the reaction that changes harmful car exhaust gases into safer substances like carbon dioxide and water.