Titration

Question 1

F

Answer 1

Formal concentration:
about moles of “original chemical formula” in solution per liter

Note: Refer to F OF TITRANT!
(F will increase in any case, since titrant is keep being added)

Question 2

Ve

Answer 2

Equivalence point:
the point where stoichiometric amount of titrant and analyte reacted

Conjugate base pair of analyte react with water to increase p().
Ex) WA,SB titrant: conjugate base of weak acid (weak base) react with water, inc. pH as it forms OH-.
See paint.

Question 3

M

Answer 3

Molar concentration:

about moles of “each chemical species” in solution per liter

Question 4

(1/2)Ve

Answer 4

Half of equivalence point:
the point where half of titrant was added to form the next compound.

the pt where half of titrant got deprotonated (if titrant was acid)

[HA]=[A-] if titrant was acid
[HB]=[B-] if titrant was base

Question 5

Le Chatlier’s principle

Answer 5

Predict effect of change in chemical rxn in species

adding more reactant -> more product

Question 6

Common ion effect

Answer 6

If there are ions of the same kind already dissolved in solution, then solubility of the ion is lower
than if there are no ions of same kind present in sol’n.

Question 7

K

Answer 7

Equilibrium constant

K=( [C]^c [D]^d / [A]^a [B]^b )

Question 8

Ka

Answer 8

Acid dissociation constant

HA-> H+ A-
Ka=( [H+][A-] ) /[HA]

∴ Bigger Ka means the acid dissociated to give out H+ more, and therefore indicates stronger acid

Question 9

pH

Answer 9

-log[H+]

14-pOH

Question 10

pKa

Answer 10

pKa=-log[Ka]

Note: just like smaller pH indicates stronger acid, smaller Ka indicates stronger acid.

Question 11

Henderson-Hasselbalch equation

Answer 11

ONLY WORK FOR WEAK ACID OR BASE
pH=pKa+log([A-]/[HA])
pOH=pKb+log([BH+]/[B-])

Question 12

Henderson-Hasselbalch equation at (1/2)Ve

Answer 12

pH=pKa if titrant was acid
pOH=pKb if titrant was base

∵log1=0
and the solution is either weak acid or base at (1/2)Ve

Question 13

Mass balance

Answer 13

Formal concentration = all form of the species

Question 14

Before Ve

Answer 14

[analyte] determines pH

Question 15

After Ve

Answer 15

[titrant] determines pH

Question 16

pF,pKa,pH

Answer 16

pH and pKa are smaller for stronger acid.
pF is small if much titrant is added (don’t relate to acidity)
UNLESS compare to pKa

Question 17

pF>7

AT Vi or Ve

Answer 17

pH=7

Since Not much F were added to solution, no pH change.
Q-what if starting pH was SA/SB, and not neutral water? Would I then need to calculate pH of starting species

Question 18

pKb given

Answer 18

DON’T do: 14-pKb to get pKa IF solution is base

DO: 14-pkb to get pKa IF solution is acid

Question 19

pKa less than pF

at Vi or Ve

Answer 19

Ka>F
strong-acid-like-behavior
(HA dissociates to give out H+ more)

pH=pF

m=1 (ignoring sign)

Question 20

pKa>pF

AT Vi or Ve

Answer 20

Ka is smaller than pF

pH is half of sum of pF and pKa, m=1/2(WA like)