Common Ion Effect and Equilibrium

The video tutorial explains the common ion effect, which occurs when a chemical with a common ion is added to a solution at equilibrium, causing a shift in equilibrium. The tutorial uses two examples: iron hydroxide with added sodium hydroxide and calcium fluoride with added sodium fluoride. It demonstrates how to calculate new ion concentrations using equilibrium expressions and RICE tables, emphasizing the simplification of quadratic equations due to small KSP values.

What is the common ion effect?

• A method to increase the solubility of a compound.

• A phenomenon where a common ion is removed from a solution.

• A technique to decrease the concentration of ions in a solution.

• A process where a common ion is added to a solution, shifting the equilibrium.

In the example with iron hydroxide, what is the common ion when sodium hydroxide is added?

• Water molecule

• Hydroxide ion

• Iron ion

• Sodium ion

Why is the solid iron hydroxide crossed out in the RICE table?

• It does not participate in the reaction.

• It is not part of the equilibrium expression.

• It has no concentration.

• It is not affected by the common ion.

What assumption is made to simplify the equilibrium calculations in the example?

• The Ksp value is very small, making x negligible.

• The concentration of added ions is very small.

• The Ksp value is large.

• The concentration of hydroxide is negligible.

In the calcium fluoride example, what is the common ion added?

• Water molecule

• Sodium ion

• Fluoride ion

• Calcium ion

How does the addition of sodium fluoride affect the equilibrium of calcium fluoride?

• Has no effect on the equilibrium.

• Shifts equilibrium to the left, decreasing calcium concentration.

• Increases the solubility of calcium fluoride.

• Shifts equilibrium to the right, increasing calcium concentration.

What is the significance of the Ksp value in these examples?

• It indicates the solubility of the compound.

• It is used to calculate the pH of the solution.

• It determines the initial concentrations of ions.

• It shows the rate of reaction.

What is the final concentration of calcium ion in the calcium fluoride example?

• 0.001 M

• 1.0 M

• 0.01 M

• 3.9 x 10^-7 M

Why is it important to understand the common ion effect?

• To predict the color change in reactions.

• To control the temperature of reactions.

• To understand shifts in equilibrium and solubility changes.

• To measure the pH of solutions.

What happens to the equilibrium when a common ion is added to a solution?

• The equilibrium shifts to the right.

• The equilibrium shifts to the left.

• The equilibrium remains unchanged.

• The equilibrium is destroyed.