UNIT 9 Complex Acid/Base Solutions Flashcards
What is a complex acid/base system?
two acid or two bases of different strengths
An acid or base that has two or more acidic or basic functional groups
Amphiprotic substance which is capable of actin as both an acid and a base
Each components in the mic can determined if….
- the concentration of the two are the same order of magnitude
- the dissociation constant for the weak acid or base is somewhat lesss than 10^-4
When titration of a stron acid and weak acid, which acid is neutralized at the first enpoint?
The strong acid
When the concentration of the two acid are on the same order of magnitues…
- the weak acid dissociation constant lies between 10^-14 and 10^-8
- the weak acid dissociation constant is higer than 10^-4
- the weak acid dissociation constant is lower than 10^-8
What does it mean “the weak acid dissociation constant lies between 10^-14 and 10^-8”
The two equivalence points: weak and stronf
Before the frist eq point the titration curve is like that of a strong acid
After the first eq, the titration curves is like that of a weak acid
Waht does it mean “the weak acid dissociation constant is higer than 10^-4”?
- the rise is H at the first eq point is small or essentially non existant
- only total number of millimoles of weak and strong acid can be determined accurately
What ode sit mean “ the weak acid dissociation constant is lower than 10^-8”?
Only the first eq point is noticable
Only the strong acid content can be determined
The weak acid has a high buffering capacoty and the second point is difficults to determine
What is a polyfunctional acid and base?
Species that have two or more acidic or basic functional groups
Each protonated species differ in that they exhibit multiple end points in a neutralization titration
How do you solve buffer solutions with a weak di basic acid and its salts
The first part consists of free acid H2A and the conjugates base NaHA
The second makes use of the NaHA and the conjugate base Na2A
What happens in the first instance of buffer soltuions?
Only of the first dissociation constant Ka is considered to calculate the concentration of H3O+
The second dissociation is neglected
What happens in the second instance of polyprotic acids in a buffere solution?
The weak acid NaHA and the conj base Na2 A make the buffer solution, the second dissociation reaction predominates and Ka2 is considered to calculate the concentration og H3O+
What is created during neutralization titrations of polyfunctional acids and bases?
Amphiprotic salts that have both acidic and basic properties
What needs to be in order to have a decent endpoint?
ration of Ka1/Ka2 needs to be greater than 10^3
What happens in the first region on a titration curve?
Treat the system as if it was a single monoprotic acid and use the dissociation constant of Ka1 to calculate [H30+]
What happens in buffer region B?
Buffer solution consisting og weak acid H2A and conjugate weak acid H2A and conjugate base NaHA
H3O+=Ka(H2A/NaHA)
