LeChatelier's Principle and Changes in Concentration

Define chemical equilibrium.

• A reaction is reversible.
• The concentration of the reactants is equal to the concentration of the products.
• The rate of a forward reaction is equal to the rate of the reverse reaction.
• The reaction stops and no further change in concentration occurs.

LeChatelier's Principle applies to

• All chemical reactions

• Reversible reactions that are at equilibrium

• Irreversible reactions

• Only the reaction N₂ + H₂ = NH₃

This symbol indicates that a reaction is ____________

• reversible
• irreversible

Which of the two graphs reaches equilibrium?

• The left one.
• The right one.
• Both of them.
• Neither.

A system at equilibrium means it is still reacting.

• True
• False

For a chemical system to be at equilibrium, the concentrations of both the reactants and the products must

• decrease

• increase

• be constant

• be equal

What is a "stress," as used when discussing LeChatelier's Principle? Check all that apply.

• A change in concentration of a reactant or product

• A change in temperature

• A change in pressure

• A bad report card

What can an equilibrium reaction do to relieve a "stress"?

• It can switch to making a different product

• It can stop

• It can "shift" toward reactants or toward products to restore equilibrium

• It can make any component appear or vanish

The principle that states that if a system at equilibrium is disturbed, the reaction will proceed in one direction or another in order to reestablish equilibrium, is known as:

• The principle of equilibrium
• Priestley’s principle
• Le Chatelier’s principle
• Faraday’s principle

2A + 3B <----> 2AB

The forward reaction forms the substance(s) __________.

• A

• B

• AB

• A + B