Chapter 3 Chemical Equilibrium Review Honors Chemistry

Flashcards about Chemical Equilibrium. The flashcards are in question and answer format.

When does chemical equilibrium exist?

The forward rate of a chemical reaction equals its reverse rate.

When is chemical equilibrium dynamic?

The forward and reverse reactions continue to occur.

What are the 3 criteria for a system to be at equilibrium?

Constant macroscopic properties, being closed, and shifting when conditions change.

What are macroscopic properties?

Properties that are large enough to be measured or observed with the unaided eye, including color, pH, temperature, and pressure.

What does it mean for a system to be closed?

No chemicals are entering or leaving the defined system.

What is steady state?

When a system’s properties are constant, but the system is open.

What does Le Châtlelier’s Principle state?

An equilibrium system subjected to a stress will shift to partially alleviate the stress and restore equilibrium.

What is an equilibrium system?

A reacting system that is at or approaching equilibrium.

What is a stress on a system?

Any action that has a different effect on the forward reaction rate than it does on the reverse reaction rate, making the forward and reverse rates UNEQUAL.

What is equilibrium position?

The relative concentrations of reactants and products at equilibrium, usually expressed as % yield.

How do equilibria respond to volume changes?

By shifting to relieve some of the added pressure or to replace some of the lost pressure.

What is osmotic pressure?

To dissolved particles what gas pressure is to gas particles.

What is partial pressure?

The gas’s part of the total gas pressure or the pressure exerted by a single gas alone in a mixture of gases.

What external factors affect reaction rates?

Reactant concentrations and temperature.

How do equilibria respond to changing temperatures?

By shifting to remove some of the added kinetic energy or to replace some of the removed kinetic energy.

Which direction, endothermic or exothermic, is more sensitive to temperature changes?

An equilibrium’s endothermic direction is more sensitive to temperature changes than its exothermic direction due to the endothermic direction’s greater activation energy

What is entropy?

The amount of thermal energy in a closed system that is not available to do work; a state of disorganization or randomness.

What are microstates?

Configurations of disorder.

What are the two natural thermodynamic drives?

The drive toward decreasing enthalpy and the drive toward increasing entropy.

What is a spontaneous process?

One that happens “on its own” with no outside influences.

What is the equilibrium expression?

The formula for the equilibrium constant in terms of the equilibrium concentrations of reactants and products.

What is the equilibrium constant?

The numerical value provided by the equilibrium expression.

What is the only way to change a chemical equation’s equilibrium constant?

Changing the temperature.

What is the trial Keq or reaction quotient (Q)?

Numerical value derived when any set of reactant and product concentrations is plugged into an equilibrium expression.