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Reactions in Aqueous Solutions I

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Properties of Aqueous Solutions of Acids & BasesAcidic properties taste sour change the colors of indicators

turn litmus red react with metals to generate H2(g)

react with carbonates and bicarbonates to form salts, carbon dioxide and water

aqueous solutions conduct electricity react with bases to produce salt and water

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Properties of Aqueous Solutions of Acids & Bases

Basic properties taste bitter feel slippery change colors of indicators

turn litmus blue react with acids to form salts and

water aqueous solutions conduct electricity

SOAP

SOAP

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Arrhenius Acid Acid - A substance that

produces hydrogen ions, H+, in aqueous solutions.

HCl H+ + Cl-

HCN H+ + CN-

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Arrhenius Base Base - A substance that

produces hydroxide, OH-, in aqueous solutions.

KOH K+ + OH-

NH3 + H2O NH4+ + OH-

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Arrhenius Theory neutralization - combination of H+

(or H3O+) with OH- strong acids - ionize 100% in water

HCl, HBr, HI, H2SO4, HNO3, HClO4

strong bases - ionize 100% in waterLiOH, NaOH, KOH, RbOH, CsOH,Ca(OH)2, Sr(OH)2, Ba(OH)2

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Arrhenius Theory total ionic equation for strong acid

with strong base

(l)O HCl Na OH Na Cl H 2-aqaq

-aqaqaqaq

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Arrhenius Theory net ionic equation for strong acid

with strong base

(l)OH OH H 2-aqaq

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Acid-Base Theories The most general theory for

common aqueous acids and bases is the BRØNSTED - LOWRY theory

ACIDS DONATE H+ IONS BASES ACCEPT H+ IONS

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Acid-Base Theories

ACIDS DONATE H+ IONS BASES ACCEPT H+ IONS

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Brønsted-Lowry Acid-Base Theory differences between Arrhenius &

Brønsted-Lowry theories reaction does not have to occur in an

aqueous solution bases do not have to be hydroxides

for example- ammonia is not a hydroxide

NH3 + H2O NH4+ + OH-

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Hydronium Ion The hydrated hydrogen ion or

hydronium ion gives aqueous solutions of acids their characteristic acidic properties.

H2O + H+ H3O+

hydronium ion

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Hydrated Hydrogen Ion H+(aq) is really H(H2O)n

+

n is a small integer = 7? H3O+ is usually used where n = 1

H3O+ H+

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Acid-Base Characteristics Solution Type Relationship Acid[H+ ] > [OH-] Neutral [H+ ] = [OH-] Base [H+ ] < [OH-]

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Brønsted–Lowry Acids An acid is a proton donor.

HNO3 + H2O H3O+ + NO3-

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Brønsted–Lowry Bases A base is a proton acceptor.

NH3 + H2O NH4+ + OH-

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Brønsted–Lowry Acids and Bases The Brønsted definition means NH3

is a BASE in water — and water is itself an ACID.

BaseAcidAcidBaseNH4

+ + OH-NH3 + H2O

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Brønsted–Lowry Acids and Bases An acid–base reaction is the

transfer of a proton from an acid to a base.

HCl + H2O H3O+ + Cl-acid1 base2

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Brønsted–Lowry Acids and Bases

When an acid gives up a proton, a conjugate base is formed that is capable of accepting a proton.

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Brønsted–Lowry Acids and Bases

HF + H2O H3O+ + F-

acid1 base2 base1acid2

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Conjugate Acid-Bases Conjugate acid-

base pairs are a reactant and a product that differ by a proton, H+.

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Conjugate Acid-Bases Conjugate acid-base pairs are a

reactant and a product that differ by a proton, H+.

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Conjugate Acid-Bases Every acid has a conjugate base,

formed by the removal of a proton from the acid.

Every base has a conjugate acid associated with it, formed by the addition of a proton to the base.

Thus H3O+ is the conjugate acid of H2O.

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Conjugate Acid-Bases

HNO2 + H2O H3O+ + NO2-

Conjugatebase

Acid BaseConjugate

acid

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Conjugate Acid-Bases

NH3 + H2O NH4+ + OH-

Conjugateacid

BaseConjugate

baseAcid

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Conjugate Acid–Base Strengths The more readily a substance

gives up a proton, the less readily its conjugate base accepts a proton.

The more readily a base accepts a proton, the less readily its conjugate acid gives up a proton.

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Conjugate Acid–Base Strengths The stronger an acid, the weaker

its conjugate base. The weaker an acid, the stronger

its conjugate base.

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Conjugate Acid–Base Strengths

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Ampholytes A substance capable of being an

acid or a base is amphoteric.

H2O + H2O H3O+ + OH-

acid1 base1acid2base2

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Bronsted-Lowry Acid-Base Theory water can be either an acid or base

in Bronsted-Lowry theory amphoteric - species that can be

either an acid or base amphiprotic - proton transfer

reactions that species behave as either an acid or base

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base acid acid base

OH O H O H OH