Equilibrium Constants and Expressions

The video tutorial covers writing equilibrium expressions, starting with basic definitions of chemical equations and equilibrium. It explains the concept of chemical equilibrium, where reactants and products reach a state where their concentrations remain constant over time. The tutorial introduces equilibrium constants, denoted by K, and how to calculate them using the concentrations of products and reactants. It discusses the importance of coefficients in the law of mass action and how to set up equilibrium expressions using concentration and partial pressure. The video concludes with practice problems and examples, highlighting the exclusion of solids and liquids from equilibrium expressions.

What is a chemical equation?

• A process to separate chemical mixtures

• A method to measure reaction rates

• A formula for calculating equilibrium constants

• A representation of a chemical reaction with reactants and products

What does the equilibrium constant (K) represent?

• The speed of a reaction

• The ratio of concentrations of products to reactants at equilibrium

• The amount of energy released in a reaction

• The temperature at which a reaction occurs

How do you solve for the equilibrium constant?

• By dividing the concentration of products by reactants

• By multiplying the concentration of products by reactants

• By dividing the concentration of reactants by products

• By adding the concentration of reactants and products

What does the law of mass action state?

• Concentrations should be subtracted from each other

• Concentrations should be divided by their coefficients

• Concentrations should be added together

• Concentrations should be raised to the power of their coefficients

What do square brackets indicate in equilibrium expressions?

• Temperature

• Pressure

• Concentration

• Volume

How is partial pressure indicated in equilibrium expressions?

• With a capital P

• With a lowercase p

• With a square bracket

• With a curly bracket

Why do solids and liquids not appear in equilibrium expressions?

• They have a variable concentration

• They are assumed to have a concentration of zero

• They are assumed to have a value of one

• They do not participate in reactions

In the equation N2 + 3H2 ⇌ 2NH3, what is the correct expression for K?

• [NH3] / ([N2]^2[H2]^3)

• [NH3]^2 / ([N2][H2]^3)

• [N2]^3[H2] / [NH3]^2

• [N2][H2]^3 / [NH3]^2

What is the KSP expression for lead chloride in equilibrium with its ions?

• [Pb^2+][Cl^-]

• [Pb^2+][Cl^-]^2

• [Pb^2+][Cl^-]^3

• [Pb^2+]^2[Cl^-]

In the reaction H2O + CO3^2- ⇌ OH^- + HCO3^-, which component is not included in the equilibrium expression?

• HCO3^-

• OH^-

• CO3^2-

• H2O