General Chemistry II - Buffers Unit

Buffers

A system that resists pH change when adding certain acid and base amounts. What is needed is a weak acid/base and its conjugate.

Buffer Capacity

The quantity of acid or base the buffer can accommodate without a significant pH change.

The buffer capacity increases

What happens when the concentration of a solution increases?

Titrations

Controlled mixing of two reactive species. They monitor some function of the reaction.

Acid-Base Titration

Monitor pH as a function of titrant added.

Titrant

The reagent in the buret; the thing being added to create the solution.

Analyte

The sample in the flask. The thing that is being manipulated with to create the solution.

Standard solution

A solution whose concentration is accurately known.

Equivalence point

Exactly equal amounts (specifically moles) of acid and base.

End point

The point where we can detect a large pH change. This thing should be as close to the equivalence point as possible.

Indicators

Things used to observe endpoint.

Two equivalence points and buffer regions

A diprotic acid will yield what?

The solubility product (Ksp)

The product of ion concentrations in equilibrium w/slightly soluble (insoluble) ionic compounds.

Solubility decreases

What happens when the value of Ksp decreases?

Solubility

The maximum amount of solid that will dissolve in one liter of pure water @ 25 degrees celcius. The amount of solid that can be dissolved in a specific volume of solution.

Saturated solution

When the solution contains maximum amount of dissolved solute.

Equilibrium shifts left and a precipitate will form.

What happens when more dissolved solute is added to the saturated solution?

The solution is unsaturated and there will be no precipitate

What happens when Q < Ksp?

The solution is saturated but there is no precipitate

What happens when Q = Ksp

The solution is supersaturated and a precipitate will occur till Q = Ksp

What happens when Q > Ksp?

Common Ion Effect

Common ions present when two compounds result in the same ion.

Ionization is reduced and the reaction shifts left, causing solubility to decrease.

What happens when there is a common ion present?

Temperature, pH value, common ions, formation of complex ions

What are factors that affect solubility?Wha

Solubility increases

What happens when a soluble complex ion is formed?