Acids & Bases
Standards:
Chem 5a. Students know the observable properties of acids,
bases, and salt solutions.Chem 5c.
Students know strong acids and bases fully dissociate and weak acids and bases partially dissociate.
What are acids?
Some are dangerous and can burn your skin
Some are safe to eat and drink
Stomach acid helps digest food
Some are dangerous and can burn your skin
Some are safe to eat and drink
Stomach acid helps digest food
Properties of Acids
Acids can be solids, liquids, or gases A group of compounds which behave A group of compounds which behave
similarlysimilarly All have pH below 7All have pH below 7 Turn Litmus paper REDTurn Litmus paper RED In an acidic solution, [H3O+]>[OH-] All donate HAll donate H++ ions in aqueous solution ions in aqueous solution
waterHCl H+(aq) + Cl- (aq)
Acids can be solids, liquids, or gases A group of compounds which behave A group of compounds which behave
similarlysimilarly All have pH below 7All have pH below 7 Turn Litmus paper REDTurn Litmus paper RED In an acidic solution, [H3O+]>[OH-] All donate HAll donate H++ ions in aqueous solution ions in aqueous solution
waterHCl H+(aq) + Cl- (aq)
Properties of Acids
Acids are generally sour in tasteStrong acids and some concentrated weak
acids are corrosive and can cause severe burns.
Generally when you see a compound with “H” in it, i.e. HCl, HCN, it indicates that compound is an acid
In dilute concentrations, acids are responsible for the sour taste in lemons, limes, vinegar & other substances
Acids are generally sour in tasteStrong acids and some concentrated weak
acids are corrosive and can cause severe burns.
Generally when you see a compound with “H” in it, i.e. HCl, HCN, it indicates that compound is an acid
In dilute concentrations, acids are responsible for the sour taste in lemons, limes, vinegar & other substances
Examples of Strong Acids
Strong acids FULLY dissociate into H+ and an anion (negative ion) when they are mixed with H2OHCl - hydrochloric acid HI - hydroiodic acidHNO3 - nitric acid HClO4 - perchloric acidHBr - hydrobromic acid H2SO4 - sulfuric acid
Strong acids FULLY dissociate into H+ and an anion (negative ion) when they are mixed with H2OHCl - hydrochloric acid HI - hydroiodic acidHNO3 - nitric acid HClO4 - perchloric acidHBr - hydrobromic acid H2SO4 - sulfuric acid
Examples of Weak Acids
Weak acids do NOT fully dissociate; they are partially ionized in their solutionsCH3COOH - acetic acid, aka vinegarHF - hydrofluoric acidHCOOH - formic acid, found in
venom of bee & ant stings
Weak acids do NOT fully dissociate; they are partially ionized in their solutionsCH3COOH - acetic acid, aka vinegarHF - hydrofluoric acidHCOOH - formic acid, found in
venom of bee & ant stings
Acid Reactions
Acid + Base Acid + Base Salt + Water Salt + Water Acid + Metal Acid + Metal Salt + Hydrogen Salt + Hydrogen Acid + Carbonate Acid + Carbonate Salt + Water + Salt + Water +
Carbon DioxideCarbon DioxideHydrochloric acids (HCl) form Hydrochloric acids (HCl) form
CHLORIDE saltsCHLORIDE saltsNitric acid (HNONitric acid (HNO33) forms NITRATE ) forms NITRATE
saltssaltsSulfuric acid (HSulfuric acid (H22SOSO44) forms ) forms
SULFATE saltsSULFATE salts
Acid + Base Acid + Base Salt + Water Salt + Water Acid + Metal Acid + Metal Salt + Hydrogen Salt + Hydrogen Acid + Carbonate Acid + Carbonate Salt + Water + Salt + Water +
Carbon DioxideCarbon DioxideHydrochloric acids (HCl) form Hydrochloric acids (HCl) form
CHLORIDE saltsCHLORIDE saltsNitric acid (HNONitric acid (HNO33) forms NITRATE ) forms NITRATE
saltssaltsSulfuric acid (HSulfuric acid (H22SOSO44) forms ) forms
SULFATE saltsSULFATE salts
What are Bases (Alkalis)?
In our home we often use In our home we often use bases to clean things. Ex: bases to clean things. Ex: Bleach and toothpasteBleach and toothpaste
In our home we often use In our home we often use bases to clean things. Ex: bases to clean things. Ex: Bleach and toothpasteBleach and toothpaste
Properties of BasesGenerally when you see a compound
with “OH” in it, i.e. NaOH, KOH, it indicates that compound is a base. OH- = hydroxide
pH greater than 7Have bitter taste, feel slippery to the
touchStrong base can also cause serious
burnsTurn red litmus paper blueAll donate OH- ions in water In a basic solution, [H3O+]<[OH-]
Generally when you see a compound with “OH” in it, i.e. NaOH, KOH, it indicates that compound is a base. OH- = hydroxide
pH greater than 7Have bitter taste, feel slippery to the
touchStrong base can also cause serious
burnsTurn red litmus paper blueAll donate OH- ions in water In a basic solution, [H3O+]<[OH-]
Properties of Bases
Example: H2O + NH3 OH- + NH4+Example: H2O + NH3 OH- + NH4+
H+ donor(acid)
H+ acceptor(base)
Examples of Strong Bases
Strong bases FULLY dissociate into OH- and a cation (positive ion) when they are mixed with H2O
The cations of these strong bases appear in the first & second groups of the periodic table LiOH - lithium hydroxide Mg(OH)2 - magnesium hydroxide NaOH - sodium hydroxide Ca(OH)2 - calcium hydroxideKOH - potassium hydroxide and more..
Strong bases FULLY dissociate into OH- and a cation (positive ion) when they are mixed with H2O
The cations of these strong bases appear in the first & second groups of the periodic table LiOH - lithium hydroxide Mg(OH)2 - magnesium hydroxide NaOH - sodium hydroxide Ca(OH)2 - calcium hydroxideKOH - potassium hydroxide and more..
Examples of Weak Acids
Weak bases do NOT fully dissociateNH3
And more…
Weak bases do NOT fully dissociateNH3
And more…
Learning Check
Describe the solution in each of the following as: 1) acid 2) base or 3)neutral.
A. ______ Soda B. ______ Soap C. ______ Coffee D. ______ Wine E. ______ Water F. ______ Grapefruit
Describe the solution in each of the following as: 1) acid 2) base or 3)neutral.
A. ______ Soda B. ______ Soap C. ______ Coffee D. ______ Wine E. ______ Water F. ______ Grapefruit
Learning Check
Describe the solution in each of the following as: 1) acid 2) base or 3)neutral.
A. _Acid__ Soda B. _Base__ Soap C. _Acid__ Coffee D. _Acid_ Wine E. _Neutral__ Water F. _Acid__ Grapefruit
Describe the solution in each of the following as: 1) acid 2) base or 3)neutral.
A. _Acid__ Soda B. _Base__ Soap C. _Acid__ Coffee D. _Acid_ Wine E. _Neutral__ Water F. _Acid__ Grapefruit
Learning Check
Identify each as characteristic of an A) acid or B) base
A. ____ Sour taste B. ____ Produces OH- in aqueous
solutions C. ____ Produces H+ in aqueous solutions D. ____ Feels slippery to the touch
Identify each as characteristic of an A) acid or B) base
A. ____ Sour taste B. ____ Produces OH- in aqueous
solutions C. ____ Produces H+ in aqueous solutions D. ____ Feels slippery to the touch
Learning Check
Identify each as characteristic of an A) acid or B) base
A. __A_ Sour taste B. __B_ Produces OH- in aqueous
solutions C. __A_ Produces H+ in aqueous solutions D. __B_ Feels slippery to the touch
Identify each as characteristic of an A) acid or B) base
A. __A_ Sour taste B. __B_ Produces OH- in aqueous
solutions C. __A_ Produces H+ in aqueous solutions D. __B_ Feels slippery to the touch
Salt Solutions
Any ionic compound formed from the reaction between an acid and a base
The reaction between an acid and a base is called a neutralization reaction
Far less corrosive than acids or bases from which they are formed
Examples:HCl + NaOH NaCl + H2OHCl + KOH KCl + H2O
Any ionic compound formed from the reaction between an acid and a base
The reaction between an acid and a base is called a neutralization reaction
Far less corrosive than acids or bases from which they are formed
Examples:HCl + NaOH NaCl + H2OHCl + KOH KCl + H2O
Learning Check
Acid, Base or Salt?
A. ______ CaCl2B. ______ KOHC. ______ Ba(OH)2
D. ______ HBrE. ______ H2SO4
Acid, Base or Salt?
A. ______ CaCl2B. ______ KOHC. ______ Ba(OH)2
D. ______ HBrE. ______ H2SO4
Learning Check
Acid, Base or Salt?
A. __salt____ CaCl2B. __base____ KOHC. __base____ Ba(OH)2
D. __acid____ HBrE. __acid____ H2SO4
Acid, Base or Salt?
A. __salt____ CaCl2B. __base____ KOHC. __base____ Ba(OH)2
D. __acid____ HBrE. __acid____ H2SO4
pH Scale
0
Acid7
Base
14
pH of common substances
Acid – Base Concentrations
pH = 3
pH = 7
pH = 11
OH-
H3O+OH-
OH-H3O+
H3O+
[H3O+] = [OH-] [H3O+] > [OH-] [H3O+] < [OH-]
acidicsolution
neutralsolution
basicsolution
co
nc
en
trat
ion
(m
ole
s/L
)
10-14
10-7
10-1
Timberlake, Chemistry 7th Edition, page 332
pH
pH = -log [H+] pH = -log [H+]