unit 3 acids and bases
DESCRIPTION
Marissa Levy Boyi Zhang Shana Zucker. Unit 3 Acids and Bases. Brönsted - Lowry. Arrhenius Acid- An acid is a substance that when dissolved increases H + concentration Base- A base is a substance that when dissolved increases OH - concentration. Lewis. Arrhenius. - PowerPoint PPT PresentationTRANSCRIPT
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UNIT 3 ACIDS AND BASES
Marissa LevyBoyi Zhang
Shana Zucker
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WHAT IS AN ACID? WHAT IS A BASE?
ArrheniusAcid- An acid is a substance that when dissolved increases
H+ concentrationBase- A base is a substance that when dissolved increases
OH- concentration
Bronsted-LowryAcid- An acid is a substance that donates a protonBase- A base is a substance that accepts a proton
LewisAcid- An acid is a substance that is an electron-pair acceptorBase- A base is a substance that is an electron-pair donor
Brönsted - Lowry
Arrhenius
Lewis
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CONJUGATE ACIDS AND BASES
What’s an acid and what is a base?NH3 + H20 ⇆ NH4+ + OH- Base Acid Conjugate Acid Conjugate Base
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WHAT IS THE DIFFERENCE BETWEEN WEAK AND
STRONG?
Strong1. Disassociate2. Ionize completely
Weak1. Disassociate2. Ionize Partially3. Have Ka or Kb
values
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STRONG SOLUTIONS AT EQUILIBRIUMHow do you calculate pH of a strong solution at equilibrium?
1.Write the equilibrium equation2.Whatever concentration you start
with is the concentration you end with
3.Calculate the pH
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STRONG SOLUTIONS AT EQUILIBRIUMHow 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 0 0-.25 M +.25 M +.25 M
0 .25 M .25 M
pOH= -log(.25)= .602 pH= 14- pOH= 13.40
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WEAK SOLUTIONS AT EQUILIBRIUM
How do you calculate pH of a weak solution at equilibrium?
1.Write the equilibrium equation2.Write the ICE equation3.Solve for X4.Calculate the pH
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WEAK SOLUTIONS AT EQUILIBRIUM
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.
3. 7.5 x 10-3 = x2/ .25 x= .0433
4. pH= -log(.0433)= 1.36
.25 M 0 0-x +x +x
.25 -x x x
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TITRATION FORMULA
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
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WRITING TITRATION EQUATIONSStrong Acid Strong BaseH+ + OH- ⇆ H₂O (l)
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WRITING TITRATION EQUATIONS
Weak Acid Strong BaseH3PO4 + OH- ⇆ H₂O (l) + H2PO4
-
Weak Acid Weak BaseHF + N2H4 HN⇆ 2H4
+ + F-
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WHAT IS A BUFFER?
Buffer1. A weak-acid base conjugate pair2. They resist changes in pH
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CALCULATING PH OF A BUFFER
pH= pKa + log (base)/(acid)pOH= pKb + log (acid)/(base)
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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/