Equilibrium Expressions and KC Values

The video tutorial explores writing equilibrium expressions, focusing on the standard format of products over reactants raised to their stoichiometric coefficients. It distinguishes between K and Q, depending on the conditions. The tutorial explains why pure substances like liquids and solids are excluded from equilibrium expressions due to their lack of molarity. It also discusses how the direction of the chemical equation and changes in stoichiometry can affect the equilibrium constant (KC). For reactions involving gases, the video introduces KP, an equilibrium expression using pressures instead of molarities.

What is the difference between K and Q in equilibrium expressions?

• K is for reactants, while Q is for products.

• K is used for concentrations at equilibrium, while Q is for any concentrations.

• K is for gases only, while Q is for liquids.

• K is a constant, while Q varies with temperature.

How is the KC value calculated in equilibrium expressions?

• By using the pressure of gases.

• By using the temperature of the reaction.

• By using the molarity of reactants and products.

• By using the volume of the container.

What is the role of stoichiometric coefficients in equilibrium expressions?

• They are ignored in the expression.

• They are subtracted from the expression.

• They are used as exponents in the expression.

• They are added to the expression.

Why are pure liquids excluded from equilibrium expressions?

• They are always in excess.

• They have a constant concentration.

• They do not have a defined molarity.

• They react too quickly.

Why can't pure solids be included in equilibrium expressions?

• They have a fixed volume.

• They do not dissolve in water.

• They do not have a defined molarity.

• They are always reactants.

What happens to the equilibrium expression if the chemical equation is reversed?

• The expression is inverted.

• The expression is doubled.

• The expression is halved.

• The expression remains the same.

How does changing the stoichiometry of a reaction affect the KC value?

• It only affects the Q value.

• It changes the KC value.

• It only affects the reactants.

• It does not affect the KC value.

What must be included with a KC value to ensure clarity?

• The volume of the container.

• The balanced chemical equation.

• The pressure of the system.

• The temperature of the reaction.

What is a KP expression used for?

• For gas-phase reactions using pressures.

• For reactions involving liquids.

• For reactions at constant temperature.

• For reactions involving solids.

In a KP expression, what replaces molarity?

• Pressure

• Temperature

• Volume

• Concentration