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111.KClO4
2.100g
3.135g
4.NaCl
5.Unsaturated (<100g)
6.20 g
7.NH3
8. KI
22The The ChemistChemistry of ry of Acids & Acids & BasesBases
The The ChemistChemistry of ry of Acids & Acids & BasesBases
33
44
55
66
Acid and BasesAcid and Bases
77
Acid and BasesAcid and Bases
88
Acid and BasesAcid and Bases
99Acids
Have a sour taste. Vinegar is a solution of acetic acid. CitrusHave a sour taste. Vinegar is a solution of acetic acid. Citrusfruits contain citric acid.fruits contain citric acid.
React with certain metals to produce hydrogen gas.React with certain metals to produce hydrogen gas.
React with carbonates and bicarbonates to produce carbon React with carbonates and bicarbonates to produce carbon dioxide gasdioxide gas
Have a bitter taste.Have a bitter taste.
Feel slippery. Many soaps contain bases.Feel slippery. Many soaps contain bases.
Bases
1010
Some Properties of Acids
Produce H+ (as H3O+) ions in water (the hydronium ion is a
hydrogen ion attached to a water molecule)
Taste sour
Corrode metals
Electrolytes
React with bases to form a salt and water
pH is less than 7
Turns blue litmus paper to red “Blue to Red A-CID”
1111
Anion Ending Acid Name
-ide hydro-(stem)-ic acid
-ate (stem)-ic acid
-ite (stem)-ous acid
Acid Nomenclature Review
No OxygenNo Oxygen
w/Oxygen w/Oxygen
An easy way to remember which goes with which…An easy way to remember which goes with which…
““In the cafeteria, you In the cafeteria, you ATEATE something something ICICky”ky”
1212
Acid Nomenclature Flowchart
h yd ro - p re fix-ic en d in g
2 e lem en ts
-a te en d in gb ecom es-ic en d in g
-ite en d in gb ecom es
-o u s en d in g
n o h yd ro - p re fix
3 e lem en ts
AC ID Ss ta rt w ith 'H '
1313
Try these
1414
1515
Some Properties of Bases
Produce OHProduce OH-- ions in water ions in water
Taste bitter, chalkyTaste bitter, chalky
Are electrolytesAre electrolytes
Feel soapy, slipperyFeel soapy, slippery
React with acids to form salts and waterReact with acids to form salts and water
pH greater than 7pH greater than 7
Turns red litmus paper to blue “Turns red litmus paper to blue “BBasic asic BBlue”lue”
1616
Some Common Bases
NaOHNaOH sodium hydroxidesodium hydroxide lyelye
KOHKOH potassium hydroxidepotassium hydroxide liquid soap liquid soap
Ba(OH)Ba(OH)22 barium hydroxidebarium hydroxide stabilizer for plasticsstabilizer for plastics
Mg(OH)Mg(OH)22 magnesium hydroxide “MOM” Milk of magnesiamagnesium hydroxide “MOM” Milk of magnesia
Al(OH)Al(OH)33 aluminum hydroxidealuminum hydroxide Maalox (antacid) Maalox (antacid)
1717
1818
Acid/Base definitions
• Definition #1: Arrhenius (traditional)
Acids – produce H+ ions (or hydronium ions H3O+)
Bases – produce OH- ions
(problem: some bases don’t have hydroxide ions!)
1919Arrhenius acid is a substance that produces H+ (H3O+) in water
Arrhenius base is a substance that produces OH- in water
2020
Acid/Base Definitions
• Definition #2: Brønsted – Lowry
Acids – proton donor
Bases – proton acceptor
A “proton” is really just a hydrogen atom that has lost it’s electron!
2121
2222
A Brønsted-Lowry acid is a proton donorA Brønsted-Lowry base is a proton acceptor
acidconjugate
basebase conjugate
acid
2323
ACID-BASE THEORIESACID-BASE THEORIESACID-BASE THEORIESACID-BASE THEORIES
The Brønsted definition means NHThe Brønsted definition means NH33 is a is a BASEBASE in in water — and water is itself anwater — and water is itself an ACIDACID
BaseAcidAcidBaseNH4
+ + OH-NH3 + H2OBaseAcidAcidBase
NH4+ + OH-NH3 + H2O
2424
Conjugate PairsConjugate Pairs
2525
2626Acids & Base Acids & Base DefinitionsDefinitions
Lewis acid - a Lewis acid - a substance that substance that acceptsaccepts an electron an electron pairpair
Lewis base - a Lewis base - a substance that substance that donatesdonates an electron an electron pairpair
Definition #3 – Lewis Definition #3 – Lewis
2727
Formation ofFormation of hydronium ion hydronium ion is also is also an excellent example.an excellent example.
Lewis Acids & BasesLewis Acids & Bases
Electron pair of the new O-H bond Electron pair of the new O-H bond originates on the Lewis base.originates on the Lewis base.
HH
H
BASE
••••••
O—HO—H
H+
ACID
2828
Lewis Acid/Base ReactionLewis Acid/Base Reaction
2929
Lewis Acid-Base Lewis Acid-Base Interactions in BiologyInteractions in Biology
• The heme group The heme group in hemoglobin in hemoglobin can interact with can interact with OO22 and CO. and CO.
• The Fe ion in The Fe ion in hemoglobin is a hemoglobin is a Lewis acidLewis acid
• OO22 and CO can act and CO can act as Lewis basesas Lewis bases
Heme group
3030
3131The The pH scalepH scale is a way of is a way of expressing theexpressing the strength strength of acids and bases. of acids and bases. Instead of using very Instead of using very small numbers, we just small numbers, we just use the use the NEGATIVE NEGATIVE power of 10 on the power of 10 on the Molarity of the HMolarity of the H++ (or (or OHOH--) ion.) ion.
Under 7 = acidUnder 7 = acid 7 = neutral 7 = neutral
Over 7 = baseOver 7 = base
3232
pH of Common pH of Common SubstancesSubstances
3333The AP Chem “BIG 6” strong acids
• HI Hydroiodic Acid
• HBr Hydrobromic Acid
• HCl Hydrochloric Acid
• HNO3 Nitric Acid
• HClO4 Perchloric Acid
• H2SO4 Sulfuric Acid
3434Calculating the pH
pH = - log [H+](Remember that the [ ] mean Molarity)
Example: If [H+] = 1 X 10-10
pH = - log 1 X 10-10
pH = - (- 10)
pH = 10
Example: If [H+] = 1.8 X 10-5
pH = - log 1.8 X 10-5
pH = - (- 4.74)
pH = 4.74
3535
Try These!Try These!
Find the pH of Find the pH of these:these:
1) A 0.15 M solution 1) A 0.15 M solution of Hydrochloric of Hydrochloric acidacid
2) A 3.00 X 102) A 3.00 X 10-7-7 M M solution of Nitric solution of Nitric acidacid
3636pH calculations – Solving for pH calculations – Solving for H+H+pH calculations – Solving for pH calculations – Solving for H+H+
If the pH of Coke is 3.12, [HIf the pH of Coke is 3.12, [H++] = ???] = ???
Because pH = - log [HBecause pH = - log [H++] then] then
- pH = log [H- pH = log [H++]]
Take antilog (10Take antilog (10xx) of both) of both sides and get sides and get
1010-pH -pH == [H[H++]][H[H++] = 10] = 10-3.12-3.12 = 7.6 x 10 = 7.6 x 10-4-4 M M *** to find antilog on your calculator, look for “Shift” or “2*** to find antilog on your calculator, look for “Shift” or “2nd nd
function” and then the log buttonfunction” and then the log button
3737pH calculations – Solving for pH calculations – Solving for H+H+
A solution has a pH of 8.5. What is the A solution has a pH of 8.5. What is the Molarity of hydrogen ions in the solution?Molarity of hydrogen ions in the solution?
pH = - log [HpH = - log [H++]]
8.5 = - log [H8.5 = - log [H++]]
-8.5 = log [H-8.5 = log [H++]]
Antilog -8.5 = antilog (log [HAntilog -8.5 = antilog (log [H++])])
1010-8.5-8.5 = [H = [H++]]
3.16 X 103.16 X 10-9-9 = [H = [H++]]
pH = - log [HpH = - log [H++]]
8.5 = - log [H8.5 = - log [H++]]
-8.5 = log [H-8.5 = log [H++]]
Antilog -8.5 = antilog (log [HAntilog -8.5 = antilog (log [H++])])
1010-8.5-8.5 = [H = [H++]]
3.16 X 103.16 X 10-9-9 = [H = [H++]]
3838
More About WaterMore About WaterHH22O can function as both anO can function as both an ACID ACID and a and a BASEBASE..
In pure water there can beIn pure water there can be AUTOIONIZATIONAUTOIONIZATION
Equilibrium constant for water = KEquilibrium constant for water = Kww
KKww = [H = [H33OO++] [OH] [OH--] =] = 1.00 x 101.00 x 10-14-14 at 25 at 25 ooCC
3939
More About WaterMore About Water
KKww = [H = [H33OO++] [OH] [OH--] = 1.00 x 10] = 1.00 x 10-14-14 at 25 at 25 ooCC
In a In a neutral neutral solution [Hsolution [H33OO++] = [OH] = [OH--]]
so Kso Kww = [H = [H33OO++]]22 = [OH = [OH--]]22
and so [Hand so [H33OO++] = [OH] = [OH--] = 1.00 x 10] = 1.00 x 10-7-7 M M
OH-
H3O+
OH-
H3O+
AutoionizationAutoionization
4040pOH
• Since acids and bases are Since acids and bases are oppositesopposites, pH , pH and pOH areand pOH are opposites opposites
• pOH does not “really” exist, but it is pOH does not “really” exist, but it is useful for changing bases to pHuseful for changing bases to pH
• pOH looks at the perspective of a pOH looks at the perspective of a basebase
pOH = - log [OHpOH = - log [OH--]]
Since pH and pOH are on opposite ends,Since pH and pOH are on opposite ends,
pH + pOH = 14pH + pOH = 14
4141
[H[H33OO++], [OH], [OH--] and pH] and pH
What is the pH of the 0.0010 M NaOH solution? What is the pH of the 0.0010 M NaOH solution?
[OH-] = 0.0010 (or 1.0 X 10[OH-] = 0.0010 (or 1.0 X 10-3-3 M) M)
pOH = - log 0.0010pOH = - log 0.0010
pOH = 3pOH = 3
pH = 14 – 3 = 11pH = 14 – 3 = 11
OR KOR Kww = [H = [H33OO++] [OH] [OH--]]
[H[H3OO++] = 1.0 x 10] = 1.0 x 10-11-11 M M
pH = - log (1.0 x 10pH = - log (1.0 x 10-11-11) = 11.00) = 11.00
4242The pH of rainwater collected in a certain region of the northeastern United States on a particular day was 4.82. What is the H+ ion concentration of the rainwater?
4343
[OH[OH--]]
[H[H++]] pOHpOH
pHpH
1010 -pOH
-pOH
1010 -pH-pH-Log[H
-Log[H++]]
-Log[OH
Log[OH
--]]
14 -
pOH
14 -
pOH
14 -
pH
14 -
pH
1.0
x 10
1.0
x 10-1
4-14
[OH[O
H-- ]]
1.0
x 10
1.0
x 10-1
4-14
[H[H
++ ]]
4444
HNO3, HBr, HI, HCl, H2SO4 and HClO4 are among the only known strong acids.
Strong and Weak Strong and Weak Acids/BasesAcids/Bases
The strength of an acid (or base) is determined by the amount of IONIZATION.
The strength of an acid (or base) is determined by the amount of IONIZATION.
4545The AP Chem “BIG 6” strong acids
• HI Hydroiodic Acid
• HBr Hydrobromic Acid
• HCl Hydrochloric Acid
• HNO3 Nitric Acid
• HClO4 Perchloric Acid
• H2SO4 Sulfuric Acid
4646Strong and Weak Strong and Weak Acids/BasesAcids/Bases
Generally divide acids and bases into Generally divide acids and bases into STRONGSTRONG or or WEAKWEAK ones. ones.
STRONG ACID:STRONG ACID:
HNOHNO3 3 (aq) + H(aq) + H22O (l) ---> HO (l) ---> H33OO+ + (aq) + NO(aq) + NO33- - (aq)(aq)
4747
• Weak acidsWeak acids are much less than 100% ionized in are much less than 100% ionized in
water.water.
One of the best known is acetic acid = CHOne of the best known is acetic acid = CH33COCO22HH
Strong and Weak Strong and Weak Acids/BasesAcids/Bases
Strong and Weak Strong and Weak Acids/BasesAcids/Bases
4848
• Strong Base:Strong Base: 100% dissociated in water.100% dissociated in water.
NaOH (aq) ---> NaNaOH (aq) ---> Na+ + (aq) + OH(aq) + OH- - (aq)(aq)
Strong and Weak Strong and Weak Acids/BasesAcids/Bases
Other common strong Other common strong bases include KOH andbases include KOH and Ca(OH)Ca(OH)22..
CaO (lime) + HCaO (lime) + H22O -->O -->
Ca(OH)Ca(OH)22 (slaked lime) (slaked lime)CaOCaO
4949
• Weak base:Weak base: less than 100% ionized in waterless than 100% ionized in water
One of the best known weak bases is One of the best known weak bases is ammoniaammonia
NHNH3 3 (aq) + H(aq) + H22O (l) O (l) NH NH44+ + (aq) + OH(aq) + OH- - (aq)(aq)
Strong and Weak Strong and Weak Acids/BasesAcids/Bases
Strong and Weak Strong and Weak Acids/BasesAcids/Bases
5050
Weak BasesWeak Bases
5151pH testing
• There are several ways to test pHThere are several ways to test pH
–Blue litmus paper (red = acid)Blue litmus paper (red = acid)
–Red litmus paper (blue = basic)Red litmus paper (blue = basic)
–pH paper (multi-colored)pH paper (multi-colored)
–pH meter (7 is neutral, <7 acid, >7 pH meter (7 is neutral, <7 acid, >7 base)base)
–Universal indicator (multi-colored)Universal indicator (multi-colored)
– Indicators like phenolphthaleinIndicators like phenolphthalein
–Natural indicators like red cabbage, Natural indicators like red cabbage, radishesradishes
5252Paper testing
• Paper tests like litmus paper and pH Paper tests like litmus paper and pH paperpaper
– Put a stirring rod into the solution Put a stirring rod into the solution and stir.and stir.
– Take the stirring rod out, and Take the stirring rod out, and place a place a dropdrop of the solution from of the solution from the end of the stirring rod onto a the end of the stirring rod onto a piece of the paperpiece of the paper
– Read and record the Read and record the color color change. Note what the color change. Note what the color indicates.indicates.
– You should only use a small You should only use a small portion of the paper. You can use portion of the paper. You can use one piece of paper for one piece of paper for severalseveral tests.tests.
5353pH paperpH paper
5454
pH meter
• Tests the voltage of the Tests the voltage of the electrolyteelectrolyte
• Converts the voltage to Converts the voltage to pHpH
• Very cheap, accurateVery cheap, accurate
• Must be calibrated with Must be calibrated with a buffer solutiona buffer solution
5555pH indicators
• Indicators are dyes that can be added that will change color in the presence of an acid or base.
• Some indicators only work in a specific range of pH
• Once the drops are added, the sample is ruined
• Some dyes are natural, like radish skin or red cabbage
5656
ACID-BASE REACTIONSACID-BASE REACTIONSTitrationsTitrations
ACID-BASE REACTIONSACID-BASE REACTIONSTitrationsTitrations
HH22CC22OO4 (aq) 4 (aq) + 2 NaOH + 2 NaOH (aq) (aq) ---> ---> NaNa22CC22OO4 (aq) 4 (aq) + 2 H+ 2 H22OO (l) (l)
acidacid basebase
Carry out this reaction using aCarry out this reaction using a TITRATIONTITRATION..
Oxalic acid,
H2C2O4
5757Setup for titrating an acid with a baseSetup for titrating an acid with a base
5858
TitrationTitrationTitrationTitration
1. Add solution from the 1. Add solution from the buret.buret.
2. Reagent (base) reacts 2. Reagent (base) reacts with compound (acid) in with compound (acid) in solution in the flask.solution in the flask.
3.3. Indicator shows when Indicator shows when exact stoichiometric exact stoichiometric reaction has occurred. reaction has occurred. (Acid = Base)(Acid = Base)
This is called This is called NEUTRALIZATIONNEUTRALIZATION
5959
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