Acids and Bases
Properties of AcidsProperties of Acids Acids taste sour Acids effect indicators
Blue litmus turns red Methyl orange turns red
Acids have a pH lower than 7 Acids are proton (hydrogen ion, H+) donors Acids react with active metals, produce H2
Ex: Reactions lab
Acids react with carbonates to produce CO2
Acids neutralize bases
Blue litmus paper turns red in contact with an acid.
Acid Base
Acids Neutralize Bases
Effects of Acid Rain on Marble(calcium carbonate)
George Washington: BEFORE
George Washington: AFTER
Acids React with Active Metals
Acids react with active metals to form salts and hydrogen gas.
Mg + 2HCl MgCl2 + H2(g)
Magnesium
•Acids Taste Sour.
Dilutions of Acids
ALWAYS ADD ACID TO WATER
This reduces the chance that it will blow up in your face due to the heat of reaction
making steam rapidly. The denser acid will sink and disperse
more evenly.
Binary Acids
• An acid that contains hydrogen
and one other element.
Naming Binary Acids
The proper method to use when naming binary acids is to begin with the hydro- prefix, use the
root of the nonmetal, and add the –ic suffix.
Oxyacids
• An oxyacid is a compound of hydrogen, oxygen, and a third element, usually a nonmetal.
Method for Naming Oxyacids• If the acid consists of one more oxygen than the
polyatomic ion with the -ate suffix, use the per- prefix, the root of the polyatomic ion and the –ic suffix.– Example HClO4 = perchloric acid
• If the acid consists of a polyatomic ion with the -ate suffix, use the root of the polyatomic ion and add –ic.– Example HClO3 = chloric acid
• If the acid consists of hydrogen and a polyatomic ion with the -ite suffix, use the root of the polyatomic ion and add –ous.– Example HClO2 = chlorous acid
• If an acid consists of one less oxygen than the polyatomic ion ending in –ite, use the hypo prefix, the root of the polyatomic ion and the –ous suffix.– Example HClO = hypochlorouc acid
Naming Acids
_________ ide (chloride, Cl1-)
_________ite (chlorite, ClO2
-) (hypochlorite, ClO-)
_________ ate (chlorate, ClO3
-) (perchlorate, ClO4
-)
Hydro____ ic acid (hydrochloric acid, HCl)
_________ic acid (chloric acid, HClO3)
(perchloric acid, HClO4)
______ous acid (chlorous acid, HClO2)
(hypochlorous acid, HClO)
Anion Acid
add H+
add H+
add H+
ions
ions
ions
Name the Acid
Acids you must know:Acids you must know:
Strong Acids
Weak Acids
Hydrochloric acid, HCl
Nitric acid, HNO3
Sulfuric acid, H2SO4
Phosphoric acid, H3PO4
Acetic acid, CH3COOH
Sulfuric Acid
Highest volume production of any chemical in the U.S.
Used in the production of paper
Used in production of fertilizers
Used in petroleum refining
Nitric AcidNitric Acid
• Used in the production of Used in the production of fertilizers fertilizers
• Used in the production of Used in the production of explosives explosives
• Nitric acid is a volatile acid Nitric acid is a volatile acid – its reactive components – its reactive components evaporate easily evaporate easily
• Stains proteins (including Stains proteins (including skin!)skin!)
Hydrochloric Acid
• Used in the pickling of steel
• Used to purify magnesium from sea water
• Part of gastric juice, it aids in the digestion of protein
• Sold commercially as “Muriatic acid”
• Muriatic Acid (HCl)– Sold commercially
– Useful for cleaning concrete– Buyer beware
Phosphoric Acid
o A flavoring agent in sodas o Used in the manufacture of
detergents o Used in the manufacture of
fertilizers o Not a common laboratory
reagent
Acetic AcidUsed in the
manufacture of plastics Used in making
pharmaceuticals Acetic acid is the acid
present in vinegar
Strength of Acids
Acids are proton (hydrogen ion, H+) donors
Strong acids are assumed to be 100% ionized in solution (good proton donors).
Weak acids are usually less than 5% ionized in solution (poor proton donors).
Acids are Proton Donors
Monoprotic acidsDiprotic acids Triprotic acids
HCl
HC2H3O2
HNO3
H2SO4
H2CO3
H3PO4
Comparison of a Monoprotic Acid to a Diprotic Acid
Strong acids such as HCl ionize almost completrly in solution, forming
hydronium ions, H3O+
H2O + HCl H3O+ + Cl-
Proton donor
Proton acceptor
Weak acids favor reverse reactions and enter chemical
equilibrium before many hydronium ions, H3O+ form.
Organic Acids
Organic acids all contain the “carboxyl” group, sometimes several of them.
The carboxyl group is a poor proton donor, so ALL organic acids are weak acids.
Examples of Organic Acids Citric acid in citrus fruit Malic acid in sour
apples Deoxyribonucleic acid,
DNA Amino acids, the
building blocks of protein
Lactic acid in sour milk and sore muscles
Butyric acid in rancid butter
The pH scale is used to measure the
strength of an acid or base. A pH of less than 7 indicates an acid. The lower the pH, the stronger the
acid.
pH of Many Common Substances
Properties of Bases
Bases taste bitter Bases effect indicators
Red litmus turns blue Phenolphthalein turns purple
Bases have a pH greater than 7 Bases are proton (hydrogen ion,H+) acceptors Solutions of bases feel slippery
Bases neutralize acids
Bases Effect Indicators
Red litmus paper turns blue in contact with a base.
Phenolphthalein turns purple in a base.
Bases Have a Bases Have a pH of greater pH of greater
than 7.than 7.
The greater The greater the pH, the the pH, the
stronger the stronger the base.base.
Bases Feel Slippery and Taste Bitter
Bases Neutralize Acids
Milk of Magnesia contains magnesium hydroxide, Mg(OH)2, which neutralizes stomach acid, HCl.
2 HCl + Mg(OH)2
MgCl2 + 2 H2O
Examples of Bases
Sodium hydroxide (lye, Drano), NaOH
Potassium hydroxide, (Caustic Potash) KOH
Magnesium hydroxide, (milk of magnesia) Mg(OH)2
Calcium hydroxide (lime), Ca(OH)2
Different Acid-Base Definitions
Svante Arrhenius first defined acids to be proton (H+) donors and bases to be hydroxide ion
(OH-) donors in aqueous solution.
• The Arrhenius model of acids and bases is summarized by the following two reactions:
Bronsted-Lowry Definition of an Acid and Base
• Bronsted-Lowry Acid- a molecule or ion that is a proton donor.
• Bronsted-Lowry Base- a molecule or ion that is a proton acceptor.
Conjugate Acid-Base Pairs
• The conjugate base of a Bronsted acid is the species that remains after an acid has donated a proton.
• The conjugate acid of a Bronsted base is the species that is formed after the base has accepted the proton.
Bronsted Conjugate Acid-Base Pairs
The conjugate of a strong acid is a weak base.The conjugate of a strong base is a weak acid.
Example of a Weak Acid Hydrofluoric Acid, HF(Hydrogen atom- Red)(Fluorine atom- Blue)
Lewis Acids and Bases
Lewis Acid- a molecule or ion that is an electron pair acceptor.Lewis Base- a molecule or ion that is an electron pair donor.
Examples of How Bases FormBronsted Base = Proton AcceptorLewis Base = Electron Pair Donor
Bases Neutralize Acids
Acid + Base SaltSalt + Water
•Orange juice + milk bad taste
•Evergreen shrub + concrete dead bush
•Under a pine tree + fertilizer white powder
•HCl + NaOH NaCl + HOH
Products of Neutralization
HCl + NaOH
H2SO4 + Ca(OH)2
HNO3 + KOH
The products of neutralization are always a ______ and _______.
NaCl + H2O
CaSO4 + 2 H2O
KNO3 + H2O
salt water
Amphoteric• When a
substance acts like an acid
under one set of conditions and
as a base under another set of
conditions.
The pH scale is a way of The pH scale is a way of expressing the strength of expressing the strength of acids and bases. Instead of acids and bases. Instead of using very small numbers, using very small numbers, we just use the NEGATIVE we just use the NEGATIVE power of 10 on the Molarity power of 10 on the Molarity of the Hof the H++ (or OH (or OH--) ion.) ion.
Under 7 = acidUnder 7 = acid7 = neutral7 = neutral
Over 7 = base Over 7 = base
Calculating the pHpH = - 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
8.2
pH:
A M
easu
rem
ent
Sca
le f
or A
cids
and
Bas
esCalculating [OH-] from pH
What is the [OH-] of a solution with pH = 4.95?
• First find [H3O+] • 4.95 = -log [H3O+]
• [H3O+] = 10-4.95 • [H3O+] = 1.12 x 10-5
• Now solve for [OH-]• [OH-] = 1 x 10-14 = 1.0 x 10-9
1.12 x 10-5
pH = -log[H3O+]
1 x 10-14 = [H3O+][OH-]
Try These!Try These!
Find the pH of these:Find the pH of these:
1)1) A 0.15 M solution of A 0.15 M solution of Hydrochloric acidHydrochloric acid
2) A 3.00 X 102) A 3.00 X 10-7-7 M M solution of Nitric solution of Nitric acidacid
pH = - log [HpH = - log [H++]]
pH = - log 0.15pH = - log 0.15
pH = - (- 0.82)pH = - (- 0.82)
pH = 0.82pH = 0.82
pH = - log 3 X 10pH = - log 3 X 10-7-7
pH = - (- 6.52)pH = - (- 6.52)
pH = 6.52pH = 6.52
pH calculations – Solving for H+pH calculations – Solving for H+pH calculations – Solving for H+pH calculations – Solving for 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” *** to find antilog on your calculator, look for “Shift” or “2or “2nd nd function” and then the log buttonfunction” and then the log button
PROBLEM: You have 50.0 mL of 3.0 M PROBLEM: You have 50.0 mL of 3.0 M NaOH and you want 0.50 M NaOH. NaOH and you want 0.50 M NaOH. What do you do?What do you do?
PROBLEM: You have 50.0 mL of 3.0 M PROBLEM: You have 50.0 mL of 3.0 M NaOH and you want 0.50 M NaOH. NaOH and you want 0.50 M NaOH. What do you do?What do you do?
Add water to the 3.0 M solution to lower its Add water to the 3.0 M solution to lower its concentration to 0.50 M concentration to 0.50 M
Dilute the solution!Dilute the solution!
PROBLEM: You have 50.0 mL of 3.0 M NaOH PROBLEM: You have 50.0 mL of 3.0 M NaOH and you want 0.50 M NaOH. What do you and you want 0.50 M NaOH. What do you do?do?
PROBLEM: You have 50.0 mL of 3.0 M NaOH PROBLEM: You have 50.0 mL of 3.0 M NaOH and you want 0.50 M NaOH. What do you and you want 0.50 M NaOH. What do you do?do?
3.0 M NaOH 0.50 M NaOH
H2O
Concentrated Dilute
But how much water But how much water do we add?do we add?
PROBLEM: You have 50.0 mL of 3.0 M NaOH PROBLEM: You have 50.0 mL of 3.0 M NaOH and you want 0.50 M NaOH. What do you and you want 0.50 M NaOH. What do you dodo??
PROBLEM: You have 50.0 mL of 3.0 M NaOH PROBLEM: You have 50.0 mL of 3.0 M NaOH and you want 0.50 M NaOH. What do you and you want 0.50 M NaOH. What do you dodo??
How much water is added?How much water is added?
The important point is that --->The important point is that --->
moles of NaOH in ORIGINAL solution = moles of NaOH in ORIGINAL solution = moles of NaOH in FINAL solutionmoles of NaOH in FINAL solution
PROBLEM: You have 50.0 mL of 3.0 M NaOH and PROBLEM: You have 50.0 mL of 3.0 M NaOH and you want 0.50 M NaOH. What do you do?you want 0.50 M NaOH. What do you do?PROBLEM: You have 50.0 mL of 3.0 M NaOH and PROBLEM: You have 50.0 mL of 3.0 M NaOH and you want 0.50 M NaOH. What do you do?you want 0.50 M NaOH. What do you do?
Amount of NaOH in original solution = Amount of NaOH in original solution =
M • V = M • V =
(3.0 mol/L)(0.050 L) = 0.15 mol NaOH(3.0 mol/L)(0.050 L) = 0.15 mol NaOH
Amount of NaOH in final solution must also Amount of NaOH in final solution must also = 0.15 mol NaOH= 0.15 mol NaOH
Volume of final solution =Volume of final solution =
(0.15 mol NaOH)(1 L/0.50 mol) = 0.30 L(0.15 mol NaOH)(1 L/0.50 mol) = 0.30 L
or or 300 mL300 mL
PROBLEM: You have 50.0 mL of 3.0 M NaOH PROBLEM: You have 50.0 mL of 3.0 M NaOH and you want 0.50 M NaOH. What do you and you want 0.50 M NaOH. What do you do?do?
PROBLEM: You have 50.0 mL of 3.0 M NaOH PROBLEM: You have 50.0 mL of 3.0 M NaOH and you want 0.50 M NaOH. What do you and you want 0.50 M NaOH. What do you do?do?
Conclusion:Conclusion:
add 250 mL add 250 mL of waterof water to to 50.0 mL of 50.0 mL of 3.0 M NaOH 3.0 M NaOH to make 300 to make 300 mL of 0.50 M mL of 0.50 M NaOH. NaOH.
3.0 M NaOH 0.50 M NaOH
H2O
Concentrated Dilute
A shortcutA shortcut
MM11 • V • V11 = M = M22 • V • V22
Preparing Solutions by Preparing Solutions by DilutionDilution
Preparing Solutions by Preparing Solutions by DilutionDilution
THE
END
Top Related