CHEM Titrations + Ksp + Buffers

Titrations are used to find an unknown by adding a

known

What’s the endpoint?

When moles of acid = moles of base

Titrations can be made with any combination of strong/weak acids and bases EXCEPT for…

Weak acid + Weak base

Titrating a strong acid with strong base means start and end points are

start at low pH and end at high pH

point of inflection =

equivalence point

OH is on the top half of the graph (above 7) and H⁺ is on the

bottom half (below 7)

At the half equivalence point pH =

pKa

when the pH is lower than the pKa, that means there is more

HA (acid) around

buffer region is around the what point?

½ equivalence point

Solubility is defined as:

How much of a compound will dissolve in a solvent to make a solution (g/L)

Molar solubility is the….

maximum concentration of a compound in a solution (M)

Saturate solution

solutions at maximum solubility

In saturated solutions concentration

= molar solubility

In unsaturated solutions concentration

< molar solubility

Unsaturated solutions…

not at maximum solubility

Supersaturated solution

above maximum solubility

supersaturated solutions have concentration

> molar solubility

Ksp indicates whether a compound is

soluble or insoluble

Ksp >> 1

is soluble (favoring aqueous products)

Ksp << 1

is insoluble (favoring solid products)

Ksp is unitless T/F

True

If Ksp > Q does a precipitate form?

no precipitate forms (forward direction)

If Ksp < Q does a precipitate form?

precipitate forms (backwards direction)

The value with the ________ Ksp will precipitate first

smallest

Smallest Ksp =

least soluble

Largest Ksp =

most soluble

Common ion effect says that

the solubility of an ionic compound is decreased in a solution that contains a common ion

adding more of a common ion will shift the equilibrium toward…

the side without it. This usually suppresses ionization and reduces solubility or acidity.

larger pKa =

smaller Ka

Ka to pKa =

-log(Ka)

pKa to Ka =

10^-pKa

pKa =

-log(Ka)

If the pKa and pH are close together, then that makes a ______ buffer

good