Equilibrium Constant Expression

The video tutorial explains the equilibrium constant expression KC, highlighting that it excludes the concentrations of reactants and products in solid-state due to their constant density. It uses the oxidation of sulphur to sulphur dioxide as an example, showing that only gaseous concentrations are included in the KC expression. The tutorial also discusses how the concentration of solids remains constant in equilibrium reactions, and any changes in solid quantity do not affect the equilibrium. Additionally, it covers equilibrium reactions in aqueous solutions, noting that the concentration of water is not included in the KC expression because it remains constant due to its large excess.

Why are solid reactants and products not included in the equilibrium constant expression KC?

• They are not present in the reaction mixture.

• Their concentration is considered constant due to density.

• They do not participate in the reaction.

• Their concentrations are too low to measure.

In the oxidation of sulfur to sulfur dioxide, which substances are included in the KC expression?

• Sulfur and oxygen

• Only sulfur

• Sulfur and sulfur dioxide

• Sulfur dioxide and oxygen

What happens to the equilibrium when the amount of solid in a reaction is changed?

• The equilibrium constant changes.

• The equilibrium shifts to the left.

• The equilibrium shifts to the right.

• The equilibrium remains unaffected.

Why is the concentration of water not included in the KC expression for reactions in aqueous solutions?

• Water is not a reactant.

• Water is present in large excess, so its concentration remains constant.

• Water does not affect the reaction rate.

• Water is not involved in the equilibrium.

In the ionization of carbonic acid in water, which ions are formed?

• Carbonate ion and hydroxide ion

• Bicarbonate ion and hydronium ion

• Bicarbonate ion and hydroxide ion

• Carbonate ion and hydronium ion