Acids and BasesAcids and Bases

AcidsAcids

• Sour tastesSour tastes

• pH: 0 – 6.9pH: 0 – 6.9

• Reacts with carbonateReacts with carbonate

to produce COto produce CO22 gas. gas.

• Turns Litmus fromTurns Litmus from

Blue to Red.Blue to Red.

• Reacts with metals to Reacts with metals to

produce hydrogen gas.produce hydrogen gas.

AcidsAcids

•Acids Solutions conduct electricity Acids Solutions conduct electricity (In ion form)(In ion form)

•Strong (99%)Strong (99%)HCl HCl (aq)(aq) + H + H22O O (l)(l) H H++ (aq)(aq)

+ Cl + Cl-- (aq)(aq)

oror

HH22SOSO44 (aq)(aq) + H + H22O O (l) (l) HH++ (aq)(aq) + + HSOHSO44

-- (aq)(aq)

•Weak or strong acids depends on how Weak or strong acids depends on how much the acid dissociates.much the acid dissociates.

BasesBases

•Bitter TasteBitter Taste

•pH: 7.1 – 14pH: 7.1 – 14

•Turns Litmus fromTurns Litmus from

Red to BlueRed to Blue

•Reacts with acids to Reacts with acids to

form salts.form salts.

•Slippery feelSlippery feel

BasesBases

•Weak or Strong depends on how much it Weak or Strong depends on how much it dissociatesdissociates..

•Weak (4%)Weak (4%)NaNa22COCO33 (aq)(aq) + H + H22O O (l)(l) Na Na++ (aq)(aq) + + COCO33

-- (aq)(aq)

•Strong (99%)Strong (99%)

NaOH NaOH (aq)(aq) + H + H220 0 (l)(l) Na Na++ (aq)(aq) + + OHOH- - (aq)(aq)

What is an What is an AcidAcid and What and What is a is a BaseBase??

• Define acid and base in terms of water.Define acid and base in terms of water.

HH22O or HOHO or HOH

HH--OHOH < <Molecular StructureMolecular Structure

HH++ = Hydrogen = Hydrogen (Acid)(Acid)

OHOH-- = Hydroxide = Hydroxide (Base)(Base)

If you have If you have more hydrogenmore hydrogen then then hydroxide, you have an acidhydroxide, you have an acid

What is an What is an AcidAcid and What and What is a is a BaseBase??

•If you have If you have more hydroxidemore hydroxide then then hydrogen you have a base. hydrogen you have a base.

HH+ + = = AcidAcid

OHOH-- = = BaseBase

HOH (HHOH (H22O) = Neutral O) = Neutral

•We measure acid and Base on the We measure acid and Base on the ““pHpH”” scale. scale.

What is an What is an AcidAcid and What and What is a is a BaseBase??

pH ScalepH Scale

•The pH scale goes from 0 The pH scale goes from 0 14 14

pH ScalepH Scale

• Acid: pH 0 – 6.9Acid: pH 0 – 6.9

• Base: pH 7.1 – 14Base: pH 7.1 – 14

• pH of 7 = Neutral pHpH of 7 = Neutral pH

Common AcidsCommon Acids

•Hydrochloric Acid = HClHydrochloric Acid = HCl

•Sulfuric Acid = HSulfuric Acid = H22SOSO44

•Nitric Acid = HNONitric Acid = HNO33

Common BasesCommon Bases

•Sodium Hydroxide = NaOHSodium Hydroxide = NaOH

•Ammonium Hydroxide = NHAmmonium Hydroxide = NH44OHOH

•Potassium Hydroxide = KOHPotassium Hydroxide = KOH

Types of AcidsTypes of Acids

•Monoprotic acids contain only one acidic hydrogen.

Types of AcidsTypes of Acids

•Diprotic contains 2 acidic hydrogens

•Triprotic contains 3 acidic hydrogens

•Polyprotic- more than 1 acidic hydrogen

Types of AcidTypes of Acid

•Most acids are oxyacids, where Most acids are oxyacids, where the acidic proton is attached the acidic proton is attached to an oxygen atom.to an oxygen atom.

– HNOHNO33 Nitric Acid Nitric Acid

– HH22SOSO44 Sulfuric Acid Sulfuric Acid

– HH33POPO44 Phosphoric Acid Phosphoric Acid

Types of AcidsTypes of Acids

•Amphoteric- can act as an acid or a base.Amphoteric- can act as an acid or a base.

HH22O + HO + H22O HO H33OO++ + + OHOH--

Acid Acid (1)(1) Base Base (1)(1) Acid Acid (2)(2) Base Base (2)(2)

The above is an autoionization of HThe above is an autoionization of H22O, O, and involves the transfer of a proton and involves the transfer of a proton from one water molecule to another to from one water molecule to another to produce a OHproduce a OH-- and H and H33OO++..

Buffers and Buffer Buffers and Buffer SolutionsSolutions•A buffered solution is one that A buffered solution is one that

““resists a change is its pHresists a change is its pH””, when , when either a hydroxide, OHeither a hydroxide, OH- - or or hydrogen, Hhydrogen, H++, are added., are added.– Blood is a good example of a buffer.Blood is a good example of a buffer.

•A buffer contains 2-components: an A buffer contains 2-components: an acid to neutralize the addition of acid to neutralize the addition of OHOH--, and a base to neutralize the , and a base to neutralize the HH++ from the addition of an acid. from the addition of an acid.

Buffers and Buffer Buffers and Buffer SolutionsSolutions

•When base (OHWhen base (OH--) is added to a ) is added to a buffer solution, the acid in buffer solution, the acid in the buffer provides Hthe buffer provides H++ ions, ions, which neutralizes the base, which neutralizes the base, thus, preventing a large thus, preventing a large change in pH.change in pH.

Buffers and Buffer Buffers and Buffer SolutionsSolutions•The bloodThe blood’’s primary buffer system is s primary buffer system is made up of carbonic acid (Hmade up of carbonic acid (H22COCO33) and ) and sodium bicarbonate(NaHCOsodium bicarbonate(NaHCO33).).

HH+ + + HCO+ HCO33--

HH22COCO33

From Acid In Buffer From Acid In Buffer Carbonic AcidCarbonic Acid

OHOH-- + H + H22COCO33 HCO HCO33-- + +

HH22OOFrom Base In Buffer Bicarbonate IonFrom Base In Buffer Bicarbonate Ion

Buffers and Buffer Buffers and Buffer SolutionsSolutions

Original Buffer pH

Added OH- ion replaced by acid ion

orAdded H+ ion replaced

by base ion

Final pH of BufferClose to original

Acids and BasesAcids and Bases

•Bases are ionic compounds Bases are ionic compounds containing containing metal cations metal cations and and the hydroxide ion, OHthe hydroxide ion, OH--..

– When a When a ““BaseBase”” completely completely dissociates in water to produce dissociates in water to produce OHOH--, it is referred to as , it is referred to as AlkalineAlkaline..

Bronsted-Lowery Acids and Bronsted-Lowery Acids and BasesBases

•Bronsted–Lowery Bronsted–Lowery AcidAcid is a is a molecule or ion that is a proton molecule or ion that is a proton (H(H++) donor.) donor.

•Bronsted-Lowery Bronsted-Lowery BaseBase is a is a molecule or ion that is a proton molecule or ion that is a proton (H(H++) acceptor.) acceptor.

Bronsted-Lowery Bronsted-Lowery

• Bronsted-Lowery Acid is a molecule Bronsted-Lowery Acid is a molecule that is a that is a Proton DonorProton Donor..

ExampleExample

HCl + NHHCl + NH33 NHNH44

+ + + Cl + Cl--

• The proton is transferred from the The proton is transferred from the hydrogen chloride to ammonia.hydrogen chloride to ammonia.

Bronsted-LoweryBronsted-Lowery

•Bronsted-Lowery Base is a molecule Bronsted-Lowery Base is a molecule that is a proton acceptor.that is a proton acceptor.

ExampleExample

HCl + NHHCl + NH33 NH NH44

+ + + Cl + Cl--

Proton Proton ProtonProton

DonorDonor AcceptorAcceptor

AcidAcid BaseBase

Dissociates / IonizesDissociates / Ionizes

•A strong acid is one that ionizes A strong acid is one that ionizes completely in an aqueous solution.completely in an aqueous solution.

•A strong acid is a strong A strong acid is a strong electrolyteelectrolyte..– Electrolyte – Any compound that Electrolyte – Any compound that conducts electricity when melted or conducts electricity when melted or dissolved in water.dissolved in water.

Dissociates / IonizesDissociates / Ionizes

•Acids that are weak electrolytes are Acids that are weak electrolytes are known as known as weak acidsweak acids..– They do not dissociate or ionize very They do not dissociate or ionize very much.much.

•Dissociation- The separation of ions Dissociation- The separation of ions that occurs when an ionic compound that occurs when an ionic compound dissolves.dissolves.

•Ionization-The process where ions Ionization-The process where ions form from a covalent compound.form from a covalent compound.

Dissociates / IonizesDissociates / Ionizes

Arrhenius Acids and Arrhenius Acids and BasesBases•An An Arrhenius Acid Arrhenius Acid is a chemical is a chemical compound that increases the compound that increases the concentration of hydrogen ions, concentration of hydrogen ions, HH++, , in an aqueous solution.in an aqueous solution.

•Arrhenius Base Arrhenius Base is a substance that is a substance that increases the concentration of increases the concentration of hydroxide ions, hydroxide ions, OHOH--, in an aqueous , in an aqueous solution.solution.

Conjugated Acid and Conjugated Acid and BasesBases• When an acid gives up a proton, it can re-When an acid gives up a proton, it can re-accept the proton and acts as a base.accept the proton and acts as a base.

HF + HHF + H22O FO F-- + + HH33OO+ +

Acid Base Conjugated Acid Base Conjugated ConjugatedConjugated

Base Base Acid Acid

• In the above reaction the water molecule is a In the above reaction the water molecule is a Bronsted-Lowery Base. The hydronium ion is Bronsted-Lowery Base. The hydronium ion is now able to donate a hydrogen proton, so it now able to donate a hydrogen proton, so it is called a conjugated acid.is called a conjugated acid.

Lewis Acids and BasesLewis Acids and Bases

•A Lewis acid is an electron-pair A Lewis acid is an electron-pair acceptor.acceptor.

•A Lewis base is an electron-pair donor.A Lewis base is an electron-pair donor.

HH++ + [ O – H ] + [ O – H ]-- H O H O

HH

Lewis Acid Lewis Base Lewis Acid Lewis Base

Graphic organizer time!Graphic organizer time!

Neutralization ReactionNeutralization Reaction

• The reaction of The reaction of an acid and base an acid and base is called a is called a neutralizationneutralization reaction because reaction because the properties of the properties of both the acid and both the acid and base are base are diminished of diminished of neutralized when neutralized when they react.they react.

Concentration of Concentration of SolutionSolution•The concentration of a solution The concentration of a solution is a measure of the amount of is a measure of the amount of the solute (solid) in a given the solute (solid) in a given amount of solvent (Liquid).amount of solvent (Liquid).

•Molarity- The number of moles of Molarity- The number of moles of a solute in one liter of a solute in one liter of solution.solution.

Molarity, M= Moles/LiterMolarity, M= Moles/Liter

Concentration of Concentration of SolutionSolution

•If 3 moles of LiCl are added to If 3 moles of LiCl are added to 100 L of water, what is the 100 L of water, what is the molarity of the solution? molarity of the solution?

3 mol/100 L = 3 mol/100 L = 0.03 M of LiCl0.03 M of LiCl

Concentration of Concentration of SolutionSolution•If you put 20.0 g of NaOH in 1-liter If you put 20.0 g of NaOH in 1-liter of water, what is the molarity (M).of water, what is the molarity (M).

20.0g NaOH 1 mole = 20.0g NaOH 1 mole = 0.5 mole0.5 mole

40.0 g NaOH40.0 g NaOH

0.5 mol/1.0 L = 0.5 mol/1.0 L = 0.5 M of NaOH0.5 M of NaOH

Concentration of Concentration of SolutionSolution•If you put 50.0 g of HCl in 2.0 If you put 50.0 g of HCl in 2.0 liters of water, what is the molarity liters of water, what is the molarity (M)?(M)?

50.0g HCl 1 mole = 50.0g HCl 1 mole = 1.37 mole1.37 mole

36.46 g HCl36.46 g HCl

1.37 mol/2.0 L = 1.37 mol/2.0 L = 0.69 M of HCl0.69 M of HCl

Concentration of Concentration of SolutionSolution•When making-up a solution:When making-up a solution:

MM11VV11=M=M22VV22

MM11 = Initial or Beginning Molarity = Initial or Beginning Molarity

VV1 1 = Initial or Beginning Volume= Initial or Beginning Volume

MM2 2 = Final or Ending Molarity= Final or Ending Molarity

VV22 = Final or Ending Volume = Final or Ending Volume

Concentration of Concentration of SolutionSolution•If you have 300mL of a 0.5 M If you have 300mL of a 0.5 M solution of HNOsolution of HNO33. What volume of . What volume of water needs to be added to get 0.8 M water needs to be added to get 0.8 M solution of HNOsolution of HNO33??

MM11 = 0.5 M = 0.5 MVV11 = 300 mL = 300 mLMM2 2 = 0.8 M= 0.8 MVV22 = ? = ?

MM11VV11=M=M22VV22

•If you have 56 mL of a 3 M If you have 56 mL of a 3 M solution of Hsolution of H22SOSO44. What volume . What volume of water needs to be added to of water needs to be added to get 0.1 M solution of Hget 0.1 M solution of H22SOSO44??

MM11 = 3 M = 3 MVV11 = 56 mL = 56 mLMM2 2 = 0.1 M= 0.1 MVV22 = ? = ?

•If you have 56 mL of a 3 M If you have 56 mL of a 3 M solution of Hsolution of H22SOSO44. What will the . What will the concentration of Hconcentration of H22SOSO4 4 be if we be if we add 1000mL (1L) of water?add 1000mL (1L) of water?

MM11 = 3 M = 3 MVV11 = 56 mL = 56 mLMM2 2 = ? M= ? MVV22 = 1000 mL = 1000 mL

•If you have 5 mL of a 12 M If you have 5 mL of a 12 M solution of HCl. What will the solution of HCl. What will the concentration of HClconcentration of HCl be if we be if we add 500mL (1L) of water?add 500mL (1L) of water?

MM11 = 12 M = 12 MVV11 = 5 mL = 5 mLMM2 2 = ? M= ? MVV22 = 500 mL = 500 mL

Acid-Base TitrationAcid-Base Titration

• The general process of determining the molarity of an acid or a base through the use of an acid-base reaction is called an acid-base titration.

Acid-Base TitrationAcid-Base Titration

•The known reactant molarity is used to find the unknown molarity of the other solution.

•Solutions of known molarity that are used in this fashion are called standard solutions.

•In a titration, the molarity of one of the reactants, acid or base, is known, but the other is unknown.