topic 10 correlates to topic 10 in review book, pages 174-188
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Unit 8: Acids and Bases
Correlates to Topic 10 in review book, pages 174-188
Unit 8: Acids and Bases
Acids = substances that react with a base; often has a low pH
May be strong or weak
Actual definition depends upon the type of acid/base
Bases = substances reacting with an acid; often has a high pH
May be strong or weak
3 major types of acids and bases here
Characteristics of Acids and Bases
Acids:o Taste souro Conduct current in
solutiono React with bases
to form water and salt
o React with some metals to make H2(g)
o Low pH
Bases:o Taste bittero Slippery/soapy
feelingo Conduct current in
solutiono React with acids
to form salt watero Have low pOH or
high pH
II. Types of Acids and Bases
1. Arrhenius 2. Bronsted-Lowry
1. Arrhenius Acid/Base
Acid = substances that release hydrogen ions in aqueous solutions
proton donors
Ex.] HCl H+ + Cl-
Base = substances that release hydroxide ions in aqueous solutions
Hydroxide donors
Ex.] NaOH Na+ = OH-
2. Bronsted-Lowry Acid/Base
Acid = any substance that can donate hydrogen ions in solutiono Proton donors
Ex.] HCl H+ + Cl-
Base = any substance that can accept hydrogen ions in solution
Proton acceptors
Ex.]NH3 + H+ NH4+
Lewis Acids and Bases [non-Regents]
Acid = any species that can accept an electron pair from another species in solution
Ex.] H+ + NH3
Base = any species that can donate an electron pair to another species in solution
NH4+
III. Strengths of Acids and Bases
STRONG acids/bases will completely dissociate [ionize] in solution
Ex.] HCl, HNO3, H2SO4, NaOH, KOH, etc.
WEAK acids/bases produce very few ions per molecule in solution
Ex.] vinegar, H3PO4, formic acid, citric acid, etc.
Acid and Base Conjugates
Acid/Base Conjugates = species that are formed in solution as a result of the dissociation of an acid or base
Ex.] HCl + NaOH Na+ + Cl- + HOH
o Cl- is the conjugate baseo Na+ is the conjugate acid
IV. Titrations
Titration = method used to determine the pH of an unknown solution
Process to find the concentration of an unknown acid/base by neutralizing it with a base/acid of known concentration
An indicator signals the equivalence point and tells that the neutralization is complete
Titrations, [continued]
Uses burets, a standard solution of known pH, an indicator, and a fixed volume of a solution with an unknown pH
Titration Formula:
MaVa = MbVb
http://www.youtube.com/watch?v=u9nOIZDdvRw
Acid-Base Reactions
Acid + Base = Salt + water
Acids and bases neutralize each other
H+ + OH- H2O
V. pH and pOH
pH = the scale, 0-14, that defines the acidity or basicity of a solution
Based on the concentration of hydrogen ions
• 0-6 = acid• 7= neutral• 8-14 = base
pOH pOH = the
measure of the concentration of OH- ions in solution
Opposite of pH
Scale 0-14• 0-6 = strong base• 7= neutral• 8-14 = acidic
Relating pH and pOH
pH + pOH = 14 always!
pH = -log[H+]
pOH = -log[OH-]
B. pH and pOH Calculations
Ex. 1] What is the pH of a solution containing 9.15 x 10-6 M H+?
Ex. 2] What is the pH of a solution containing [OH-] = 8.11 x 10-5 M in 350.mL of solution?
C. Indicators Indicators = compounds that
change color when the pH changes
oColor changes indicate the pH of the solution!
oUse several indicators to pinpoint the final pH!
Indicators: Table M
Find the pH using the indicator and its color in the solution…
Tutorial on indicators:
http://www.kentchemistry.com/links/AcidsBases/Indicators.htm
Expanded Indicators Chart
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