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Chemistry Lecture ’94 B. Rife CHS
Text: Modern Chemistry; Holt, Rinehart & Winston 1993
Acids and Bases Chapter 16
Homework:
1
Section Reviews (pg 469,475,479,483,486)
2
Reviewing Concepts:
(all)
(pg 487-8)
3
Problems (all black / red EC) (pg 488-9)
4
Chapter/Section Review (Handout)
Exam Date _ Thursday 5/ 4
DUE DATE
16.1 Acids
16.1A List five general properties of aqueous acids. ( )
1. ACIDS HAVE SOUR TASTE.
2. ACIDS CONTAIN HYDROGEN, AND SOME REACT WITH ACTIVE METALS TO LIBERATE
HYDROGEN GAS (H2)
3. ACIDS CHANGE THE COLOR OF DYES KNOWN AS “ACID-BASE” INDICATORS.
4. ACIDS REACT WITH BASES TO PRODUCE SALTS AND WATER.
5. ACIDS ARE ELECTROLYTES.
16.1B Define and give an example of a traditional acid, a Bronsted acid, and a Lewis acid. ( )
ARRHENIUS MODEL:
ACIDS PRODUCE HYDROGEN IONS IN AQUEOUS SOLUTIONS.
BASES PRODUCE HYDROXIDE IONS IN AQUEOUS SOLUTIONS.
FOR EXAMPLE:
HNO3 + H2O ---> NO3- + H3O+
KOH + H2O ---> OH- + K+
EACH HNO3 MOLECULE PRODUCES A HYDROGEN ION
EACH KOH MOLECULE PRODUCES A HYDROXIDE ION
BRONSTED-LOWRY MODEL:
ACIDS ARE PROTON (HYDROGEN ION) DONOR.
BASES ARE PROTON (HYDROGEN ION) ACCEPTOR.
FOR EXAMPLE:
HCl + H2O ---> Cl- + H3O+
EACH HCl MOLECULE DONATES A PROTON AND THUS IS A BRONSTED-LOWRY ACID.
EACH H2O MOLECULE ACCEPTS A PROTON AND THUS IS A BRONSTED-LOWRY BASE.
LEWIS MODEL:
ACIDS ARE ELECTRON PAIR ACCEPTORS.
AN ATOM OR MOLECULE THAT REACTS BY FORMING AN ADDITIONAL COVALENT
BOND (USUALLY TO COMPLETE AN ELECTRON OCTET)
BASES ARE ELECTRON PAIR DONORS.
FOR EXAMPLE:
BF3 (aq) + F- ---> BF4- (aq)
16.1C Explain the difference between a strong acid and a weak acid, and give an example of each. ( )
STRONG ACID IS A STRONG ELECTROLYTE AND IONIZES 100% IN AQUEOUS SOLUTION.
EXAMPLES: HYDROCHLORIC, NITRIC, SULFURIC
WEAK ACID IS A WEAK ELECTROLYTE AND IONIZES ONLY A SMALL PERCENT IN AQUEOUS
SOLUTION.
EXAMPLES: ACETIC, CARBONIC, PHOSPHORIC
MONOPROTIC ACID IS AN ACID THAT CAN DONATE ONE PROTON PER MOLECULE. (HCl, HNO 3)
POLYPROTIC ACID IS AN ACID THAT CAN DONATE MORE THAN ONE PROTON PER MOLECULE.
DIPROTIC ACID IS AN ACID THAT CAN DONATE TWO PROTONS PER MOLECULE. (H 2SO4)
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TRIPROTIC ACID IS AN ACID THAT CAN DONATE THREE PROTONS PER MOLECULE. (H3PO4)
MINERAL ACIDS ARE ACIDS MADE FORM MINERALS.
(NITRIC, SULFURIC, PHOSPHORIC, HYDROCHLORIC)
ORGANIC ACIDS ARE ORGANIC COMPOUNDS THAT CONTAIN AN ACID GROUP, THE CARBOXYL
GROUP -COOH (ACETIC)
16.1D Explain and use the systems for naming common binary acids and oxyacids. ( )
BINARY ACIDS - CONTAIN HYDROGEN AND ONE OF THE MORE ELECTRONEGATIVE ELEMENTS
(USUALLY HALOGENS)
THE ACID IS NAMED WITH THE PREFIX HYDRO- , THE ROOT NAME OF THE SECOND
ELEMENT, AND THE SUFFIX -IC.
HCl (g)
HYDROGEN CHLORIDE
HCl (aq)
HYDROCHLORIC ACID
HF (g)
HYDROGEN FLUORIDE
HF (aq)
HYDROFLUORIC ACID
OXYACIDS - CONTAIN HYDROGEN, OXYGEN, AND A THIRD ELEMENT
WHEN THE ACID FORMED IS FROM AN ANION WITH -ATE SUFFIX,
THE ACID NAME IS THE ROOT NAME AND THE SUFFIX -IC
WHEN THE ACID FORMED IS FROM AN ANION WITH -ITE SUFFIX,
THE ACID NAME IS THE ROOT NAME AND THE SUFFIX -OUS
SO4
-2
SULFATE ION
H2SO4 SULFURIC ACID
SO3-2
SULFITE ION
H2SO3 SULFUROUS ACID
ClO4-
PERCHLORATE ION
HClO4 PERCHLORIC ACID
ClO3
CHLORATE ION
HClO3 CHLORIC ACID
ClO2-
CHLORITE ION
HClO2 CHLOROUS ACID
HYPOCHLORITE ION
HClO
-
-
ClO
THE PREFIX PER- MEANS ABOVE.
HYPOCHLOROUS ACID
THE PREFIX HYPO- MEANS BELOW.
16.1E Write the electron-dot structures for common oxyacids. ( )
SEE FIGURE 16-5 AND 16-6
16.1F Name five acids commonly found in industry and/or the laboratory, and describe their nature (strong
or weak, the number of ionizable hydrogen atoms, whether inorganic or organic, etc.). ( )
SULFURIC ACID - IS THE MOST MANUFACTURED CHEMICAL. IT IS USED IN FERTILIZER
MANUFACTURE, PETROLEUM REFINING, AND METALLURGY. IT IS THE BATTERY ACID OF
AUTOMOBILE BATTERIES.
SULFURIC ACID HAS TWO IONIZABLE HYDROGEN ATOMS, ONE STRONG, ONE WEAK, AND
IS AN INORGANIC ACID.
PHOSPHORIC ACID - IS USED IN THE MANUFACTURE OF FERTILIZERS, DETERGENTS, CERAMICS,
AND PHOSPHORUS CONTAINING CHEMICALS.
PHOSPHORIC ACID HAS THREE IONIZABLE HYDROGEN ATOMS, ALL WEAK, AND IS AN
INORGANIC ACID.
NITRIC ACID - IS USED IN THE MANUFACTURE OF EXPLOSIVES, RUBBER, DYES, PLASTICS, AND
DRUGS.
NITRIC ACID HAS ONE IONIZABLE HYDROGEN ATOM, STRONG, AND IS AN INORGANIC
ACID.
HYDROCHLORIC ACID - IS USED IN THE MANUFACTURE OF IRON AND STEEL, CLEANING
AGENTS AND FOOD PROCESSING. TECHNICAL GRADE, CONCENTRATED HCl ACID IS SOLD
IN HARDWARE STORES UNDER THE NAME OF MURIATIC ACID.
HYDROCHLORIC ACID HAS ONE IONIZABLE HYDROGEN ATOM, STRONG, AND IS AN
INORGANIC ACID.
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ACETIC ACID - IS USED IN THE MANUFACTURE OF PLASTICS AND FOOD PROCESSING. ACETIC
ACID IS SOLD UNDER THE NAME OF GLACIAL ACID. VINEGAR CONTAINS 4 TO 8 PERCENT
ACETIC ACID.
ACETIC ACID HAS ONE IONIZABLE HYDROGEN ATOM, WEAK, AND IS AN ORGANIC ACID.
16.2 Bases and Acid-Base Reactions
16.2A List five general properties of aqueous bases. ( )
1.
2.
3.
4.
5.
BASES HAVE A BITTER TASTE.
DILUTE AQUEOUS SOLUTIONS OF BASES FEEL SLIPPERY TO THE SKIN.
BASES, LIKE ACIDS, CHANGE THE COLOR OF DYES KNOWN AS “ACID-BASE” INDICATORS.
BASES REACT WITH ACIDS TO PRODUCE SALTS AND WATER.
BASES ARE ELECTROLYTES.
16.2B Define and give an example of a traditional base, a Bronsted base, and a Lewis base.
( )
SEE LECTURE NOTES 16.1B
A SOLUTION THAT CONTAINS OH- FROM A SOLUBLE BASE IS REFERRED TO AS ALKALINE.
16.2C Define and recognize traditional, Bronsted , and Lewis acid-base reactions. ( )
ARRHENIUS MODEL:
NEUTRALIZATION REACTION IS ONE IN WHICH AN ACID (HYDRONIUM IONS) AND A BASE
(HYDROXIDE IONS) REACT IN STOICHIOMETRIC PROPORTIONS, SO THAT THERE IS NO
EXCESS OF EITHER IN THE FINAL SOLUTION. THE PRODUCTS ARE WATER AND A SALT.
HCl (aq) + NaOH (aq) ---> NaCl (aq) + H2O (l)
ACID + BASE ---> SALT + WATER
ME
HCl (aq) + NaOH (s) --->
Acid
CIE
+
+
Base
-
H (aq) + Cl (aq) + Na+(aq) + OH-(aq) ---> Na+(aq) + Cl-(aq) + H2O(l)
Salt
NIE
+
+ Water
-
H3O (aq) + OH (aq) ---> 2H2O (l)
A SALT IS AN IONIC COMPOUND COMPOSED OF A METAL CATION OF AN AQUEOUS BASE AND
THE ANION FROM AN AQUEOUS ACID.
BRONSTED-LOWRY MODEL:
ACIDS ARE PROTON (HYDROGEN ION) DONOR.
BASES ARE PROTON (HYDROGEN ION) ACCEPTOR.
FOR EXAMPLE:
H2O + NH3 ---> NH4+ + OHB-L
B-L
ACID
BASE
EACH H2O MOLECULE DONATES A PROTON AND THUS IS A BRONSTED-LOWRY ACID.
EACH NH3 MOLECULE ACCEPTS A PROTON AND THUS IS A BRONSTED-LOWRY BASE.
LEWIS MODEL:
ACIDS ARE ELECTRON PAIR ACCEPTORS.
AN ATOM OR MOLECULE THAT REACTS BY FORMING AN
ADDITIONAL COVALENT BOND (USUALLY TO COMPLETE AN ELECTRON OCTET)
BASES ARE ELECTRON PAIR DONORS.
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FOR EXAMPLE:
Al+3 + 6 H2O ---> [Al(H2O)6]+3
LEWIS
LEWIS
ACID
BASE
HERE THE Al+3 ION ACCEPTS ONE ELECTRON PAIR FROM EACH OF SIX WATER MOLECULES.
16.2D Explain the difference between a strong base and a weak base, and give an example of each. ( )
STRONG BASE IS A STRONG ELECTROLYTE AND IONIZES 100% IN AQUEOUS SOLUTION.
EXAMPLES: SODIUM HYDROXIDE, POTASSIUM HYDROXIDE
WEAK BASE IS A WEAK ELECTROLYTE AND IONIZES ONLY A SMALL PERCENT IN AQUEOUS
SOLUTION.
EXAMPLES: CALCIUM HYDROXIDE, AMMONIA
ANIONS THAT HAVE A WEAK ATTRACTION FOR PROTONS ARE WEAK BRONSTED-LOWERY BASES.
16.3 Relative Strengths of Acids and Bases
16.3A Define conjugate acid, conjugate base, and conjugate acid-base pair. ( )
CONJUGATE ACID IS THE SPECIES FORMED WHEN A PROTON IS ADDED TO A BASE. THE
CONJUGATE ACID IS THE SPECIES THAT DONATES A PROTON WHEN THE REACTION IS
REVERSED.
CONJUGATE BASE IS WHAT REMAINS OF AN ACID MOLECULE AFTER A PROTON IS LOST.
CONJUGATE ACID-BASE PAIR ARE THE TWO SPECIES RELATED TO EACH OTHER BY THE
DONATING AND ACCEPTING OF A SINGLE PROTON. IN THE CONJUGATE ACID-BASE PAIR,
THE ACID TYPICALLY HAS ONE MORE PROTON THAN THE BASE.
16.3B Write the formula for the conjugate acid of a base and for the conjugate base of an acid. ( )
GENERAL FORMULA:
HA (aq) + H2O (l) ---> H3O+ (aq) + A- (aq)
ACID
BASE CONJUGATE
CONJUGATE
ACID
BASE
CONJUGATE ACID-BASE PAIR: HA & AH2CO3 (aq) + H2O (l) ---> H3O+ (aq) + HCO3- (aq)
ACID
BASE
CONJUGATE
CONJUGATE
ACID
BASE
CONJUGATE ACID-BASE PAIR: H2CO3 & HCO316.3C Explain why the conjugate base of a strong acid is a weak base and why the conjugate acid of a strong
base is a weak acid. ( )
THERE IS A COMPETITION FOR THE PROTON (H+) BETWEEN THE CONJUGATE BASE AND THE
WATER.
IF THE CONJUGATE BASE IS WEAK, THE PROTON READILY DISSOCIATES AND IS ATRACTED TO
THE WATER FORMING A HYDRONIUM (A STRONG ACID).
16.3D Explain why proton-transfer reactions favor the production of the weaker acid and the weaker base.
THE WEAKER ACID HAS A GREATER ATTRACTION FOR THE PROTON, THUS PROTONTRANSFER REACTIONS FAVOR THE PRODUCTION OF THE WEAKER ACID AND THE
WEAKER BASE.
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16.3E Define an amphoteric substance, and give an example. ( )
A SUBSTANCE IS SAID TO BE AMPHOTERIC IF IT CAN BEHAVE EITHER AS AN ACID OR AS A BASE.
WATER IS THE MOST COMMON AMPHOTERIC SUBSTANCE.
THIS IS DEOMONSTRATED IN THE AUTOIONIZATION OF WATER, WHICH INVOLVES THE
TRANSFER OF A PROTON FROM ONE WATER MOLECULE TO ANOTHER TO PRODUCE A
HYDROXIDE ION AND A HYDRONIUM ION.
H2O + H20 ---> H30+ + OHIN THIS REACTION, ONE WATER MOLECULE ACTS AS AN ACID BY FURNISHING A PROTON, AND
THE OTHER ACTS AS A BASE BY ACCEPTING THE PROTON.
AUTOIONIZATION CAN OCCUR IN LIQUID AMMONIA
NH3 + NH3 ---> NH4+ + NH216.4 Oxides, Hydroxides, and Acids
16.4A Define acid anhydride and basic anhydride, and give an example of each. ( )
AN OXIDE THAT REACTS WITH WATER TO FORM AN ALKALINE SOLUTION IS REFERRED TO AS A
BASIC OXIDE, OR A BASIC ANHYDRIDE. THE TERM ANHYDRIDE MEANS WITHOUT
WATER.
METAL OXIDES FORM BASIC SOLUTIONS. Na2O, CaO
AN OXIDE THAT REACTS WITH WATER TO FORM AN ACID SOLUTION IS REFERRED TO AS A ACIDIC
OXIDE, OR A ACID ANHYDRIDE.
NONMETAL OXIDES FORM ACIDIC SOLUTIONS. CO2, SO3, NO2
16.4B Write the equations for the reactions of acid anhydrides and basic anhydrides with water. ( )
SYNTHESIS REACTIONS OF NONMETAL OXIDES PRODUCE OXYACIDS
CO2 (g) + H2O (l) ---> H2CO3 (aq)
SO3 (g) + H2O (l) ---> H2SO4 (aq)
NO2 (g) + H2O (l) ---> HNO3 (aq)
(ACID RAIN)
SYNTHESIS REACTIONS OF METAL OXIDES PRODUCE BASES
CaO (s) + H2O (l) ---> Ca(OH)2 (s)
Na2O (s) + H2O (l) ---> 2NaOH (s)
16.4C Discuss the general location in the Periodic Table of elements that form acidic, basic, and amphoteric
oxides. ( )
BASIC - LEFT AND CENTER
ACIDIC - RIGHT
AMPHOTERIC - CENTER
AMPHOTERIC OXIDES HAVE BEHAVIOR INTERMEDIATE BETWEEN THAT OF ACIDIC AND BASIC
OXIDES.
ALUMINUM OXIDE Al2O3 IS A TYPICAL AMPHOTERIC OXIDE.
16.4D Name some properties that determine whether an OH group will be basic or acidic. ( )
ANY FEATURE OF A MOLECULE THAT INCREASES THE POLARITY OF THE O-H BOND INCREASES
THE ACIDITY OF A MOLECULAR COMPOUND.
ELECTRONEGATIVE ATOMS (C,N,S,Cl) OR ADDITIONAL OXYGEN ATOMS BOTH INCREASE THE
POLARITY OF THE O-H BOND AND MAKE THE SPECIES MORE ACIDIC.
CHROMIUM FORMS OH COMPOUNDS THAT ARE ACIDIC, BASIC, & AMPHOTERIC.
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16.5 Chemical Reactions of Acids, Bases, and Oxides
16.5A Describe four types of reactions involving aqueous acids. ( )
1. ACIDS REACT WITH MANY METALS
NONOXIDIZING ACIDS REACT WITH METALS
(REPLACEMENT OF HYDROGEN IN AN ACID BY A METAL)
2Al (s) + 6HCl (aq) ---> 2Al(Cl)3 + 3H2 (g)
FORMING HYDROGEN GAS AND SALTS
OXIDIZING ACIDS REACT WITH METALS
Cu (s) + 4HNO3 (conc.) ---> 2Cu(NO3)2 + 2NO2 (g) + 2H2O (l)
FORMING NITRIC OXIDE GAS, WATER, AND SALTS
2. ACIDS REACT WITH METAL OXIDES
CuO (s) + H2SO4 (aq) ---> CuSO4 (aq) + H2O (l)
FORMING WATER AND SALTS
3. ACIDS REACT WITH CARBONATES
CaCO3 (s) + 2HCl (aq) ---> CO2 (g) + CaCl2 (aq) + H2O (l)
FORMING CARBON DIOXIDE, WATER AND SALTS
16.5B Describe two types of reactions involving aqueous bases. ( )
4. HYDROXIDES REACT WITH NONMETAL OXIDES
CO2 (g) + Ca(OH)2 (aq) ---> CaCO3 (s) + H2O (l)
2CO2 (g) + Ca(OH)2 (aq) ---> Ca(HCO3) (s)
FORMING SALT AND WATER OR JUST SALT
16.5C Describe three common types of reactions involving oxides. ( )
5. METAL OXIDES REACT WITH NONMETAL OXIDES
MgO (s) + CO2 (g) ---> MgCO3 (s)
FORMING SALT
16.5D Predict the products of reactions involving aqueous acids, aqueous bases, and oxides. ( )
N2O5 + H2O --->
N2O5 + H2O ---> 2HNO3
SYNTHESIS REACTIONS OF NONMETAL OXIDES PRODUCE OXYACIDS
Ba(OH)2 + 2CO2 --->
Ba(OH)2 + 2CO2 ---> Ba(HCO3)2
4. HYDROXIDES REACT WITH NONMETAL OXIDES
Mg + HCl --->
Mg + 2HCl ---> MgCl2 + H2
1. ACIDS REACT WITH MANY METALS
NONOXIDIZING ACIDS REACT WITH METALS
(REPLACEMENT OF HYDROGEN IN AN ACID BY A METAL)
MgO + P4O10 --->
6MgO + P4O10 ---> 2Mg3(PO4)2
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5. METAL OXIDES REACT WITH NONMETAL OXIDES
MgO (s) + CO2 (g) ---> MgCO3 (s)
FORMING SALT
H2SO4 + Mg(OH)2 --->
H2SO4 + Mg(OH)2 ---> MgSO4 + 2H2O
Titration is a procedure for carrying out a chemical reaction between two solutions by the controlled addition
(from a buret) of one solution to the other. In a titration a means must be found, as by the use of an
indicator, to locate the equivalence point.
Volumetric Analysis is a process involving titration of one solution with another.
Titrant is a solution of known concentration
Analyte is a solution of unknown conc. being analyzed
Stoichiometric (Equivalence) Point of a titration is the condition where the reactants are in stoichiometric
proportions. They consume each other, and neither reactant is in excess.
Indicator is a substance that is added in a small amount to a titration mixture and changes color at the
equivalence point
Endpoint of a titration is the point in the titration where the indicator used changes color. A properly chosen
indicator for a titration must have its end point correspond as closely as possible to the
equivalence point of the titration reaction.
Strong Acid - Strong Base
H+(aq) + OH-(aq) ---> H2O (l)
Weak Acid-Strong Base
HB (aq) + OH-(aq) ---> B- (aq) + H2O (l)
Strong Acid - Weak Base
H+(aq) + NH3 (aq) ---> NH4+ (aq)