Intro to Acids and BasesChapter 16.1

Properties of Acids and Bases

•Acids and bases have a variety of properties that help us differentiate between them.

•If something a neither acidic or basic, it is said to be neutral.

•Let’s make a table to compare the properties of acids and bases

ACID BASE

Taste

Slippery?

Litmus

Phenol-phthalein

ACID BASE

Taste Sour Bitter

Slippery?

Litmus

Phenol-phthalein

ACID BASE

Taste Sour Bitter

Slippery? No Yes

Litmus

Phenol-phthalein

ACID BASE

Taste Sour Bitter

Slippery? No Yes

Litmus Red Blue

Phenol-phthalein

ACID BASE

Taste Sour Bitter

Slippery? No Yes

Litmus Red Blue

Phenol-phthalein

Colorless Red

acid

base

PHENOLPHTHALEIN

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Acid/Base Theories

•Numerous scientists have discussed the behavior of acids and bases in a chemical reaction.

•The two main models for acids and bases are Arrhenius and Bronsted-Lowry

• In many acid base reactions, H+ ions are transferred to water create H3O+, known as the hydronium ion.

•Let’s look at a table to compare how acids and bases behave

ACID BASE

ArrheniusMake H+

ion in water

Make OH-

ion in water

[H3O+] to [OH-]

Bronsted/Lowry

ACID BASE

ArrheniusMake H+

Ion in water

Make OH-

Ion in water

[H3O+] to [OH-]

[H3O+] > [OH-] [H3O+] < [OH-]

Bronsted/Lowry

ACID BASE

ArrheniusMake H+

Ion in water

Make OH-

Ion in water

[H3O+] to [OH-]

[H3O+] > [OH-] [H3O+] < [OH-]

Bronsted/Lowry

proton (H+) donor

proton(H+) acceptor

Examples of Acid and Base Reactions•Arrhenius Acid: •HNO3 —> H+ + NO3

-

•Arrhenius Base: •KOH —> K+ + OH-

•B-L Acid: •HCl + H2O —> Cl- + H3O+

•B-L Base: •NH3 + H2O —> NH4

+ + OH-

Strong vs Weak Acids and Bases•Acids and Bases are classified by the

degree to which they dissociate as strong or weak

•Strong acids and bases dissociate completely, therefore, they are excellent conductors of electricity.▫Acids: HCl, HBr, H2SO4, H2SO4

▫Bases: NaOH, KOH•Weak acids and bases dissociate partially,

therefore they are only OK conductors of electricity▫Acids: HF, H2S▫Bases: NH3

Concentrated vs Dilute

•Strong and weak refers to the amount of dissociation.

•Concentrated and dilute refers to the molarity of the solution.

•Concentration does NOT affect whether an acid or base is strong or weak.

Types of Acids

•There are a variety of types of acids that you need to know:

•Monoprotic acid: acid that can supply one H+ ion per molecule. Ex. HCl, HBr

•Polyprotic acid: acid that can supply more than one H+ ion per molecule. Ex. H2SO4

Types of Acids•Binary acid: acid composed of 2 elements

(one is always H). Ex. HBr, HF•Ternary acid: acid composed of hydrogen

plus two other elements. Ex H3PO4

•An acid could be both monoprotic and binary, like HCl. However, some acids like H2S is only binary.

•An acid could be both polyprotic and ternary, like H2SO4. However, some acids like HNO3 is ternary and monoprotic.

Naming Acids: A Review

•Acids without oxygen▫Prefix “hydro”, name of element, change

ending to “ic”•Acids with oxygen

▫No “hydro”▫If polyatomic has an “ate” ending, change

the “ate” to “ic”▫If polyatomic has an “ite” ending, change

the “ite” to “ous”

Conjugate Acid-Base Pairs

•The reaction of B-L acid and bases produces the conjugate base and acid

•Conjugate base- the particle formed when an acid has donated a H+ ion. It will act as the base by accepting a proton in the reverse reaction.

•Conjugate acid- the particle formed when a base has accepted a H+ ion. It will act as the acid by donating a proton in the reverse reaction

Examples

•H2CO3 + H2O —> HCO3- + H3O+

•Acid Base C.B C.A

•NH3 + H2O —> NH4+ + OH-

•BaseAcid C.A. C.B.

Neutralization Reaction

•A neutralization reaction is a reaction between an acid and a base in a aqueous solution to produce a salt and water.

•A salt is an ionic compound made up of the cation from the base and the anion from the acid.

•Acid + Base —> Salt + Water•Despite the name, neutralization

reactions do not always results in a neutral solution

Neutralization Reactions

•The reaction of a strong acid plus a weak base forms a solution that is acidic

•The reaction of a weak acid and a strong base forms a solution that is basic.

•What do you think would happen if you react a weak acid and a weak base or a strong acid and a strong base?

•They form a neutral solution