Chemistry-Osterberg
Ch. 15-Acids/Bases
Name ___________________________
Date __________________ Hour______
Page 1 of 3
Chapter 15 Objectives
Obj. 1-Acids and Bases (Arrhenius Definition)
• Acids increase the hydronium ion (H3O+1) concentration
Strong Acid
Weak Acid
Ionizes Completely
Incomplete ionization
+1
Forms many H3O ions
Forms very few H3O+1 ions
HNO3, HCl
HC2H3O2
Good conductor of electricity
Poor conductor of electricity
because more ions. (strong
because more ions. (weak
electrolytes)
electrolytes)
• Strength of acids does not depend on concentration, but how much it ionizes.
• Acids are usually liquid solutions, solids, or gases that taste sour.
• Bases increase the hydroxide ion (OH-1) concentration.
Strong Base
Weak Base
Ionizes Completely
Incomplete ionization
-1
Forms many OH ions
Forms very few OH-1 ions
NaOH
Good conductor of electricity
Poor conductor of electricity
because more ions. (strong
because more ions. (weak
electrolytes)
electrolytes)
• Acids are usually liquid solutions and solids that are slippery to touch and
taste bitter.
• Many cleaners are alkaline (basic).
• Strength of acids and bases does not depend on concentration, but how much it
ionizes.
Obj. 2-Brønsted-Lowry Classification
• The Brønsted-Lowry definitions are more general definitions than the Arrhenius
definitions, and include more substances as acids and bases, like gases and
solids.
• Acid donates a proton (usually a H+1) to another substance.
• HCl + H2O → H3O+1 + Cl -1
Monoprotic Acid (1 H)
+1
-1
• H2SO4 + H2O → H3O + HSO4
Diprotic Acid (2 H)
+1
-1
• H3PO4 + H2O → H3O + H2PO4
Triprotic Acid (3 H)
• Base accepts a proton from another substance.
• NH3 + H2O  NH4+1 + OHBase Acid
Chemistry-Osterberg
Ch. 15-Acids/Bases
Name ___________________________
Date __________________ Hour______
Page 2 of 3
• Conjugate acid is the acid that forms (on the product side) when the base accepts
a proton.
• Conjugate base is the base that forms (on the product side) when the acid
donates a proton.
• NH3 + H2O ↔ NH4+ + OHBase Acid Conjugate Acid Conjugate Base
Obj.3 -pH and Indicators
• The pH scale is a scale from 1 to 14 that indicates the strength of an acid or base.
(see p.546)
• pH < 7 is acidic; pH=7 is neutral; pH > 7 is basic
• Indicators are compounds that can reversibly change color depending on the pH
of the solution.
Red Litmus
Blue Litmus
Phenolphthalein
Acids
Red
Red
Clear
Bases
Blue
Blue
Pink
Obj. 4-pH and pOH Calculations
• pH stands for power of Hydrogen.
• As [H+1] increases, the pH decreases.
• pH Equations
pH = -log [H+1]
pOH = -log [OH-]
pH + pOH = 14
• Ex1: What is the pH of a 0.00010 M solution of HCl, a strong acid? HCl → H+1 + Cl-
HCl → H +1 + Cl−1
pH = −log[H +1 ]
[H +1 ] = 0.00010 M
pH = −log(0.00010) pH = 4
• Ex2: What is the pH of 0.0136 M solution of Ba(OH)2 (Strong base)?
Ba(OH) 2 → Ba +2 + 2OH −1
[OH −1 ] = 2x0.0136 M = 0.0272M
€
pOH = −log[OH −1 ] pOH = −log(0.0272) pOH = 1.60
pH + pOH = 14
pH +1.60 = 14 pH = 12.4
• Ex3: What is the [H+1] and the [OH-1] of a solution that has a pH of 8?
€
pH = −log[H +1 ]
pH + pOH = 14
8 = −log[H +1 ] [H +1 ] = 1x10 −8 M
8 + pOH = 14 pOH = 6
pOH = −log[OH −1 ] 6 = −log[OH −1 ] [OH −1 ] = 1x10 −6 M
Chemistry-Osterberg
Ch. 15-Acids/Bases
Name ___________________________
Date __________________ Hour______
Page 3 of 3
Obj. 5-Neutralization
• A reaction that involves an acid and a base as reactants is called a neutralization
reaction, usually neutral water is formed. The dissolved salt ions remain, but they
just spectate.
• Example: HCl + NaOH → NaCl + H2O
Obj.6-What is a titration?
• Neutralization occurs when quantities of H+1 & OH- combine to form H2O.
• A titration is a method to determine the concentration of an acid or base by adding
a solution of known volume and concentration until neutralization is complete,
which can be seen by a color change. (see p.552-553)
• A standard solution is the solution of known concentration, which is usually the
one in the buret. (Also known as the titrant.)
• Equivalence point is the point in titration when neutralization is complete.
• End point is the point at which the indicator changes color. If an indicator is
used, it is usually phenolphthalein b/c it changes from pink to clear at a pH of
about 7.
• Color change is not always exact. The
most accurate method for determining if
you reach the equivalence point is to
make a titration curve.
• A titration curve is a graph that plots
the pH against the titrant volume.
• Use pH meter to make a titration
curve, the middle of steepest slope is
the equivalence point.
Obj.7-Buffer solutions
• Buffer solutions prevent changes in pH
• Usually a solution of a weak acid and its
conjugate base of equal concentrations
that neutralizes small amounts of acids or bases added to it.
• Used in many things: food, shampoo, blood