Equilibrium Expressions in Chemistry

The video tutorial explains the difference between homogeneous and heterogeneous equilibria. Homogeneous equilibria involve reactants and products in the same phase, typically gases. Heterogeneous equilibria involve different phases, and the equilibrium position does not depend on the amounts of pure solids or liquids. The tutorial provides examples, such as calcium carbonate and water decomposition, to illustrate how equilibrium expressions are written and how solids and liquids are excluded from these expressions. It also discusses the inclusion of water vapor in equilibrium expressions when it is in the gas phase.

What is the main difference between homogeneous and heterogeneous equilibria?

• Heterogeneous equilibria involve only gases.

• Heterogeneous equilibria involve substances in the same phase.

• Homogeneous equilibria involve substances in the same phase.

• Homogeneous equilibria involve substances in different phases.

In a homogeneous equilibrium, what is typically the phase of the substances involved?

• Solid

• Liquid

• Gas

• Plasma

Why do pure solids and liquids not affect the position of a heterogeneous equilibrium?

• Their concentrations change during the reaction.

• They are not present in the reaction.

• Their concentrations remain constant.

• They are always in the gas phase.

In the equilibrium involving calcium carbonate, which component is included in the equilibrium expression?

• Carbon dioxide

• All components

• Calcium carbonate

• Calcium oxide

What happens to the equilibrium expression when solids are involved in a reaction?

• Solids increase the reaction rate.

• Solids are included in the expression.

• Solids are excluded from the expression.

• Solids change the equilibrium constant.

For the reaction of pure water decomposing into gases, which components are included in the equilibrium expression?

• Oxygen gas only

• Pure water only

• Hydrogen gas and oxygen gas

• Hydrogen gas only

If water is in the form of vapor in a reaction, how does it affect the equilibrium expression?

• It is excluded from the expression.

• It changes the reaction completely.

• It is included in the expression.

• It has no effect on the expression.

In a reaction where water is a liquid, how is it treated in the equilibrium expression?

• It is included as a reactant.

• It is included as a product.

• It is excluded from the expression.

• It is included only if it is a gas.

Which phase change would cause water to be included in the equilibrium expression?

• Solid to liquid

• Liquid to gas

• Solid to gas

• Gas to liquid

What is the equilibrium constant expression for a reaction involving only gases?

• It includes all reactants and products.

• It excludes all reactants and products.

• It includes only solids.

• It includes only liquids.