5A4 Equilibrium in Ionic Solutions Flashcards
Explain and predict how equilibrium is reached in ionic solutions, including the common ion effect.
Define:
electrolyte
A substance that conducts electricity when melted or dissolved.
Electrolytes dissociate into ions, allowing electrical current to flow.
What type of bonding is typically found in electrolytes?
Ionic bonding
Ionic bonds are characteristic of electrolyte compounds, such as salts and acids.
Fill in the blanks:
Ions are electrically charged particles formed when atoms _____ or _____ electrons.
lose, gain
Ions form when atoms lose or gain electrons, resulting in positive or negative charges.
List three examples of strong electrolytes.
- Sodium chloride (NaCl)
- Potassium chloride (KCl)
- Sulfuric acid (H₂SO₄)
Strong electrolytes fully dissociate into ions, which contribute to high electrical conductivity.
What are weak electrolytes?
Substances that only partially dissociate into ions when dissolved, leading to lower conductivity.
An example is acetic acid (vinegar).
Define:
nonelectrolyte
A substance that does not conduct electricity when dissolved or melted.
Nonelectrolytes do not form ions in solution, which prevents them from conducting electricity.
List three examples of nonelectrolytes.
- Sugar (sucrose)
- Acetone
- Ethyl alcohol
These compounds do not dissociate into ions, making them nonelectrolytes.
How can you test if a substance is an electrolyte or nonelectrolyte?
By setting up an electrical circuit with a battery and measuring the current flow through the solution.
A lightbulb and ammeter help determine whether current flows, indicating electrical conductivity.
What is the difference between electrolytes and nonelectrolytes?
Electrolytes dissociate into ions; nonelectrolytes do not.
Nonelectrolytes remain neutral when dissolved.
What is the effect of concentration on conductivity?
Higher concentrations of ions lead to greater conductivity.
Strong electrolytes conduct more electricity as their concentration of ions increases.
What is the main factor determining the electrical conductivity of a weak electrolyte?
The proportion of dissociated ions in the solution.
Weak electrolytes only partially dissociate, resulting in fewer ions and lower conductivity.
True or False:
Urea is a nonelectrolyte.
True
Urea does not dissociate into ions when dissolved, so it is considered a nonelectrolyte.
What is an aqueous solution?
A homogeneous mixture in which a substance is dissolved in water.
Electrolytes and nonelectrolytes can both form aqueous solutions.
What happens when sodium chloride dissolves in water?
Sodium chloride dissociates into Na⁺ and Cl⁻ ions.
Equation: NaCl(solid) ⇄ Na+(dissolved) + Cl−(dissolved).
What is the solubility product constant (Ksp)?
It is the equilibrium constant for the solubility reaction of a solid dissolving in a liquid.
Ksp quantifies how much of a substance can dissolve in a liquid at saturation.
Which factor does NOT influence the solubility product constant (Ksp)?
The amount of solid added to the solution.
Ksp is independent of the amount of solid, as only the concentration of ions in solution affects it.
How does temperature affect the Ksp value?
Ksp increases with temperature for most solutes.
Temperature affects solubility, thus changing Ksp values.
Fill in the blank:
A large Ksp indicates that a substance is _____ soluble.
more
Large Ksp values mean that a substance dissolves well in solution.
Define:
molar solubility
It is the number of moles of a substance that can dissolve in 1 liter of solution to reach saturation.
Molar solubility reflects the maximum solute concentration before the solution becomes saturated.
True or False:
Ksp can be calculated from ion concentrations.
True
If ion concentrations are known, Ksp can be calculated using the solubility product equation.
What does a small Ksp value indicate about a substance’s solubility?
The substance has a low solubility.
A low Ksp means the substance does not dissolve much in solution.
Higher Ksp indicates greater solubility of a substance.
List two factors that affect the Ksp value.
- Temperature
- pH
Ksp values change with temperature and sometimes pH.
What is the Ksp expression for a solubility equilibrium involving a substance dissolving into ions?
Ksp = [A]x[B]y
This formula is derived from the reaction AxBy(s)→xA(aq)+yB(aq).
The expression depends on the stoichiometry of the reaction.
The Ksp calculation requires known concentrations of dissolved ions.
What ion concentrations are used to calculate Ksp?
The concentrations of the ions in solution, NOT the solid.
Only ions in the aqueous phase are used in the Ksp expression.
True or False:
Molar solubility and Ksp are always directly related.
False
Molar solubility can be calculated from Ksp, but they are not the same value.
Fill in the blank:
The solubility product constant (Ksp) represents the equilibrium between a solid and its _____ in a saturated solution.
ions
Ksp is the constant that describes the solubility equilibrium for salts dissolving in water.
What is the common ion effect?
It is the decrease in solubility of a salt when a common ion is added to the solution.
Increasing the concentration of one ion can shift the equilibrium, reducing solubility.
What principle explains the common ion effect?
Le Chatelier’s principle
This principle states that reactions will shift to maintain equilibrium when changes occur.
Which ions are involved in the common ion effect?
Ions that are:
- Already present in the solution.
- Shared between solutes.
The presence of common ions affects the solubility and ionization of compounds.
What happens when an uncommon ion is added to a solution?
It can increase solubility by creating favorable ion-ion interactions.
Uncommon ions do not participate in the equilibrium, so they can make the solute more soluble.
True or False:
Transition metals always follow the common ion effect.
False
Transition metals can form complex ions, which may alter their solubility and bypass the common ion effect.
What is the role of ammonia in the solubility of silver chloride (AgCl)?
Ammonia forms a complex ion with silver, increasing its solubility.
This is an example of how transition metals can behave differently than other salts in the common ion effect.
What happens when chlorine ions are added to a solution with silver and copper ions?
Silver chloride (AgCl) precipitates out, but copper does not.
This is due to the differing solubility product constants (Ksp) of AgCl and copper salts.
What does the common ion effect do to the ionization of weak acids?
It decreases the ionization of weak acids in acidic solutions.
The presence of additional hydrogen ions shifts the equilibrium toward the undissociated form.
What effect does the common ion have on weak bases in basic solutions?
It decreases their ionization.
The increased concentration of hydroxide ions affects the dissociation of weak bases.
List one way the common ion effect can be used in chemistry.
To selectively precipitate ions from a solution.
For example, adding chloride ions can separate silver from copper ions.
When does the uncommon ion effect occur?
When the addition of ions not involved in the equilibrium increases solubility.
This effect contrasts with the common ion effect by making the system less stable.
What is the impact of adding hydrogen ions to a solution of acetic acid?
It reduces the ionization of acetic acid.
The added hydrogen ions shift the equilibrium towards the protonated form of acetic acid, reducing its dissociation.
