Definitions
What is the definition of a Bronsted-Lowry acid and base?
Acid- proton donor
Base- proton acceptor
What does the half-equivalence point in the buffering region tell us?
pH=pKa
Rank the acidity (weak --> strong)
pKa: 4.56, 2.89, 9.65, 3.45, 12.2
12.2, 9.65, 4.56, 3.45, 2.89
How can you tell how many protons are used in a titration curve?
Count the number of equivalence points
If pKa is small, what does that tell us about acidity?
If Ka is small, what does that tell us?
small pKa= more acidic
small Ka= less acidic
What is the definition of an Arrhenius acid and base?
Acid- dissociates into H+ in water (aqueous solution)
Base- dissociates into OH- in water (aqueous solution)
What is the pH of a solution if on a titration curve, the pKa of the half-equivalence point is 3.67 at 100 mL?
3.67
Calculate the pH of 0.50 M H2S+H2O
Ka= 9.1*10^-8
3.67
What happens if you have a strong acid and strong base titration?
The pH is 7 at equivalence point, there are no buffer regions
What are the 5 strong acids?
What are some strong bases?
What makes a species strong?
Acids: HCl, HI, HBr, HNO3, H2SO4
Bases: NaOH, Ca(OH)2, KOH
What is the equivalence point on a titration curve?
Where the moles of the acid=moles of the base
A buffer solution contains 0.36 M sodium acetate (CH3COONa) and 0.45 M acetic acid (CH3COOH), Ka = 1.58*10^-5. What is the pH of this buffer solution?
4.7
What is the pOH is Ka is 9.45*10^-10?
4.975
How do you find the initial pH on a titration curve if given molarity and Ka?
What would you use for a buffer if the pH is 5.43?
pKa: 8.57, 5.56, 6.78, 4.02
5.56
What is a buffer and how is it made?
A buffer is a solution that is resistant to pH change.
It is made of a weak species and its conjugate.
You need to produce a buffer solution that has a pH of 5.270. You already have a solution that contains 10.0 mmol (millimoles) of acetic acid. How many millimoles of sodium acetate will you need to add to this solution? The pKa of acetic acid is 4.752.
32.96 mmoles sodium acetate
What is the concentration of protons in:
11 M NH3 + H2O?
Kb= 1.8*10-5
Kw= 1*10^-14
7.12*10^-13
Consider the titration of 30.0 mL of 0.166 M of KX with 0.154 M HCl. The pKa of HX= 8.090.
(a) What is the pH of the original solution before addition of any acid?
(b) How many mL of acid are required to reach the equivalence point?
(c) What is the pH at the equivalence point?
a) 10.66
b) 32.3 mL
c) 4.59
What are the conjugates of these species:
CO32-
CH2CH2CH2COOH
NH4+
H2SO4
HCO3-
CH2CH2CH2COO-
NH3
HSO4-
What is a Lewis acid?
Acceptor of a lone pair of electrons
Make a buffer with a pKa of 6.35 that has a pH of 6.29. Its total solute concentration is 0.27 M. How many grams of each species will we need if we add 0.25 L? (A- = 20.2 g/mol, HA= 13.45 g/mol)
0.631 grams of A-
0.484 grams of HA
Calculate all values of pH, pOH, [H+], and [OH-] unless given for each:
You have 70 mL of 0.6M H2CO3 in its deprotonated state. You titrate it with 0.3M HI. Find pH at the half-equivalence points.
(pKa1: 6.35 pKa2: 10.32)
Draw and Label a Titration Graph
Buffering Region(s), Half-Equivalence Point(s), Equivalence Point(s), Volume, and Major Species
Will Draw on Board
HO-C-C-C-OH
C-C-C-NH3
both of the hydrogens on the oxygen
one of the hydrogens on the nitrogen