Transcript Unit 3 Acids and Bases

Marissa Levy
Boyi Zhang
Shana Zucker
Arrhenius
Acid- An acid is a substance that when dissolved increases
H+ concentration
Base- A base is a substance that when dissolved increases
Brönsted - Lowry
Lewis
OH- concentration
Lewis
Acid- An acid is a substance that is an electron-pair
acceptor
Arrhenius
Base- A base is a substance that is an electron-pair donor
Bronsted-Lowry
Acid- An acid is a substance that donates a proton
Base- A base is a substance that accepts a proton
What’s an acid and what is a base?
NH3 + H20 ⇆ NH4+ + OHBase
Acid
Conjugate Acid
Conjugate Base
Strong
1. Disassociate
2. Ionize
completely
Weak
1. Disassociate
2. Ionize Partially
3. Have Ka or Kb
values
How do you calculate pH of a strong solution at equilibrium?
1. Write the equilibrium equation
2. Whatever concentration you start
with is the concentration you end
with
3. Calculate the pH
How do you calculate pH of a strong solution at equilibrium?
0.25 M of HClO3 in water.
KOH(aq) + H20 (l) ⇆ K+ (aq) + OH- (aq)
.25 M
-.25 M
0
pOH= -log(.25)= .602
pH= 14- pOH= 13.40
0
+.25 M
.25 M
0
+.25 M
.25 M
How do you calculate pH of a weak solution at equilibrium?
1. Write the equilibrium equation
2. Write the ICE equation
3. Solve for X
4. Calculate the pH
How do you calculate pH of a solution at equilibrium?’
A 0.25 M Phosphoric solution is prepared in water.
Ka = 7.5 x 10-3
1. H3PO4 + H₂O (l) ⇆ H+ + H2PO4- Ka = 7.5 x 10-3
2.
.25 M
-x
.25 -x
0
+x
x
3. 7.5 x 10-3 = x2/ .25
x= .0433
4. pH= -log(.0433)= 1.36
0
+x
x
N1C1V1= N2C2V2
If 15.0 mL of HCN is completely titrated with 25.0 mL
of 0.100 M NaOH calculate the concentration of
HCN.
1(C1) (15.0)= 1(.100)(25.0)
C1= .167 M
Strong Acid Strong Base
H+ + OH- ⇆ H₂O (l)
Weak Acid Strong Base
H3PO4 + OH- ⇆ H₂O (l) + H2PO4-
Weak Acid Weak Base
HF + N2H4 ⇆ HN2H4+ + F-
Buffer
1. A weak-acid base conjugate pair
2. They resist changes in pH
pH= pKa + log (base)/(acid)
pOH= pKb + log (acid)/(base)
Sources
http://chemistry.about.com/od/acidsbase
1/ss/titrationcurves_2.htm
 http://www.chemistry.wustl.edu/~edudev/
LabTutorials/Buffer/Buffer.html
 http://www.quickmeme.com/meme/36jbu
2/
