CFR: Solubility Equilibria

These flashcards cover key concepts related to solubility equilibria, chemical equilibrium constants, and factors affecting solubility and equilibrium.

What condition must be met for a chemical system to be at equilibrium?

The rate of the forward reaction must equal the rate of the reverse reaction.

What is an equilibrium constant (K)?

A number that expresses the ratio of the concentrations of products to reactants at equilibrium, with each concentration raised to the power of its stoichiometric coefficient.

When is a solid omitted from the equilibrium constant expression?

When the concentration of the solid does not change, as its density is fixed.

What happens to the equilibrium position if the concentration of a reactant is increased?

The equilibrium will shift to the right, favoring the formation of products.

What is Le Chatelier’s Principle?

If a stress is applied to a system at equilibrium, the system will shift to minimize that stress.

Which factors can be considered a stress on a system at equilibrium?

Change in concentration, pressure, volume, or temperature.

What does it mean if K >> 1 for a reaction?

It indicates that the products are favored at equilibrium.

How do you calculate the solubility product (Ksp)?

Ksp = [Dissolved ions] raised to the power of their respective coefficients.

What's the relationship between solubility and pH in some salts?

The solubility of some salts can increase or decrease depending on the pH of the solution.

What effect does the common ion have on solubility?

The presence of a common ion decreases the solubility of a salt.

What is molar solubility?

The number of moles of a substance that can be dissolved in 1 liter of solution upon reaching saturation.

What is the solubility product constant (Ksp) of CaF2?

Ksp = [Ca2+][F-]^2.

Why is Ksp considered only one value for a given solid at a particular temperature?

Because it quantifies the saturated concentration of ions in equilibrium with the solid.

What is the common ion effect?

A decrease in the solubility of a salt when a common ion is added to the solution.

How does temperature generally affect the solubility of solids?

The solubility of most solids increases with an increase in temperature.

What happens to the solubility of an ionic compound in acidic solutions?

It may increase if the ions produced are weak bases, as the H+ ions will drive the equilibrium to the right.

What is the formula to find the solubility of lead(II) iodide (PbI2)?

Ksp = [Pb2+][I-]^2.

What can affect the solubility of drugs in formulations?

The choice of counterion and the concentration of ions in the surrounding solution.

How can you determine the molar solubility from the Ksp?

By rearranging the Ksp expression for the salt and solving for molarity.

What is an example of a salt that has a low Ksp and is used for a specific clinical purpose?

Barium sulfate, used as a radiocontrast agent.

What does Ksp indicate about solubility when comparing different salts?

It can indicate potential solubility but not directly for salts that produce different numbers of ions.

Why are stoichiometric coefficients important in equilibrium constant expressions?

They determine the power to which the concentrations are raised in the K expression.

How does the equilibrium expression differ between gases and solids?

Only gaseous and aqueous species are included; solids and pure liquids are omitted.

When writing an equilibrium constant expression, what do you need to remember about solids and liquids?

Their concentrations do not change and thus are not included.

What impact do ionic interactions have in dissolution processes?

Ionic interactions can either enhance or hinder the dissolution of ionic solids in water.

What is the significance of knowing the Ksp value in chemistry?

It helps predict whether a precipitate will form in a solution and to what extent a salt can dissolve.

What type of relationship between the forward and reverse reactions does K describe?

Kquantifies the equilibrium position based on concentrations of products and reactants.

Which type of reactions would include an equilibrium constant with dissolved ions only?

Reactions that form solutions from solids or gases.

What is the effect of increasing the pressure on a gas-phase reaction at equilibrium?

It will favor the side of the reaction with fewer gas molecules.

In a saturated solution, what is the relationship between the rate of dissolution and the rate of precipitation?

They are equal at saturation.

What can be inferred if K is less than 1?

Reactants are favored at equilibrium.

What does the stoichiometry of a reaction determine in terms of equilibrium constants?

It influences the coefficients in the K expression.

How does common ion effect change the solubility of Ag2CrO4 in the presence of AgNO3?

It reduces the solubility of Ag2CrO4 because of the additional Ag+ ions present.

Which factor can cause an increase in hydroxide concentration and thereby affect equilibrium?

Increase in pH of the solution.

What is the role of the solid in solubility equilibria?

It establishes an equilibrium with its ions in a saturated solution.

How is the dissolution of CaF2 represented in a solubility equilibrium expression?

CaF2(s) ⇌ Ca2+(aq) + 2F-(aq).

What does Ksp tell about the solubility of salts at a particular temperature?

It indicates the maximum concentration of ions that produce a saturated solution.

What is the relationship between molar solubility and Ksp values among salts that dissociate into the same number of ions?

A higher Ksp typically corresponds to a higher molar solubility.

What would happen to the concentration of a pure liquid in an equilibrium expression?

It remains constant and is not included in the equilibrium expression.

How does the concentration of solute in solution relate to achieving saturation?

It must reach a level where the rate of dissolution equals the rate of precipitation.

Why would a clinician choose barium sulfate for imaging studies?

Due to its low solubility, reducing absorption and toxicity during X-ray procedures.

What is the importance of recognizing the common ion effect in drug formulation?

It helps predict and enhance drug solubility and availability for absorption.