Acidity and Basicity

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E E X X P P E E R R I I M M E E N N T T 11 11

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Introduction

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Acids

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

 Any solution that releases hydrogen ionsAny solution that releases hydrogen ions

when added to water and has a

when added to water and has a pH of lesspH of less

than 7.0



 pH pH_–_–it measureit measures the s the acidity oacidity of f a liquid a liquid byby

measuring

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PROPERTIES OF ACIDS :



 Sour tasteSour taste



 Litmus paper blue turns redLitmus paper blue turns red



 Reactions with metal oxide and hydroxideReactions with metal oxide and hydroxide



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Bases

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

 Substances which combines with acidSubstances which combines with acid

and also known as Alkaline substance.

and also known as Alkaline substance. 

 Compound that furnishes the hydroxideCompound that furnishes the hydroxide

ions.

ions. 

 Compound that gives or Compound that gives or donate hydroxyldonate hydroxyl

ions in water or other substances.



 HydroxylHydroxyl_–_–unit that composed of one or unit that composed of one or

more atom of hydrogen and one of

oxygen.

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PROPERTIES OF BASES :



 SlipperySlippery



 Soapy feeling and a biting , bitter tasteSoapy feeling and a biting , bitter taste



 Red litmus blue , turn Red litmus blue , turn methyl organic frommethyl organic from

red to yellow

red to yellow 

 Turn Turn phenolphthalein phenolphthalein from from colorless colorless toto

red

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Procedures

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Using the pH Paper

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pH paper pH paper in test in test solution solution • • DipDip • • For 10For 10 seconds seconds Color Chart Color Chart •

• Match theMatch the color

color

obtained in obtained in the test

the test sol’nsol’n

Record Repeat

•

• With other With other test solutions test solutions

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Using the pH Meter

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Buffer Buffer Solution Solution

•

•Immerse theImmerse the

electrode

•

•After that,After that,

rinse the rinse the electrode with electrode with distilled water distilled water •

•Wipe withWipe with

tissue

First Solution First Solution

•

•Dip theDip the

electrode

•

•Get the pHGet the pH

reading reading • •RecordRecord Distilled Distilled Water Water •

•Rinse theRinse the

electrode

•

•Wipe it withWipe it with

tissue paper

Repeat Repeat

•

•With other testWith other test

solutions

solutions Keep theKeep the

electrode electrode immersed in immersed in distilled distilled water when water when not inuse not inuse..

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Samples

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Chemical Chemical Formula Formula Structural Structural Formula Formula Functional Functional Group Group Acetic

Acetic Acid Acid CHCH₃₃COOHCOOH CarboxyclicCarboxyclic Acid Acid

Monochloro-acetic acid

acetic acid ClCHClCH22COOHCOOH

Carboxyclic Carboxyclic Acid, Alkyl Acid, Alkyl Halides Halides Acetone (CH

Acetone (CH₃₃))₂₂CO CO KetoneKetone

Acetamide CH

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Chemical Chemical Formula Formula Structural Structural Formula Formula Functional Functional Group Group Glysine NH

Glysine NH₂₂CHCH₂₂COOHCOOH

Amines, Amines, Carboxyxlic Carboxyxlic Acid Acid Lysine C Lysine C₆₆HH₁₄₁₄NN₂₂OO₂₂ Amines, Amines, Carboxyxlic Carboxyxlic Acid Acid Isopropyl Isopropyl Alcohol

Alcohol (CH(CH33))22CHOH CHOH AlcoholAlcohol

Phenol Phenol CC66HH55OHOH Alcohol, Alcohol, Aromatic Aromatic Compound Compound

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Chemical

Chemical Formula Formula Structural Structural FormulaFormula

Commercial Commercial Vinegar Vinegar C C₂₂HH₄₄OO₂₂ Calamansi Calamansi Juice Juice CC66HH88OO77 Spoiled

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Arrhenius

Concept

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

 Svante Arrhenius Svante Arrhenius , , a Swedish chemist whoa Swedish chemist who

received a Nobel prize i

received a Nobel prize in 1903 for his work n 1903 for his work

on electrolytes, focused on

on electrolytes, focused on what ionswhat ions

were formed when acids and bases

dissolved in water.

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

 One of the properties that acids andOne of the properties that acids and

bases have in common is that they are

electrolytes-electrolytes--they-they form ions when theyform ions when they

dissolve in water.

dissolve in water. 

 He came up with the concept or ideaHe came up with the concept or idea

that

that acids dissociated in water toacids dissociated in water to

give hydrogen ions (H

give hydrogen ions (H++₎₎ _and_and

that

that bases dissociated in water to givebases dissociated in water to give

hydroxide ions. (OH

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Examples:

HCl

HCl HH++ _{+ Cl}_{+ Cl}-

-An acid, like HCl, is something that

An acid, like HCl, is something that

dissociates in water to give hydrogen ion.

NaOH

NaOH HH++ _{+ Cl}_{+ Cl}-

-A base, like NaOH, is something that A base, like NaOH, is something that dissociates in water to give hydroxide ion. dissociates in water to give hydroxide ion.

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

Arrhenius focused on the idea that

acids and bases

split into ions

when

they dissolved in water.



In a sense, the Arrhenius concept

focuses on what the chemical

contains

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Brønsted-Lowry

Concept

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

 With the Brønsted-Lowry concept weWith the Brønsted-Lowry concept we

usually refer to a

usually refer to a hydrogen ionhydrogen ion asas

a proton.

a proton. 

 That is because aThat is because a protonproton is all that is leftis all that is left

when a hydrogen atom loses an electron

to become an ion.

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Brønsted Acids



 Proton (HProton (H++) Donor.) Donor. 

 When an acid reacts, the When an acid reacts, the protonproton

is

is transferredtransferred from one chemical tofrom one chemical to

another.

another. 

 The chemical which accepts the proton isThe chemical which accepts the proton is

a base.