Acids, Bases, and Acids, Bases, and SaltsSalts

Chapter 23 Chapter 23

sections 1-3sections 1-3

Acids, Bases, and SaltsAcids, Bases, and Salts

Section 1 Acids & Bases Section 1 Acids & Bases slides 3-18slides 3-18

Section 2 Strength of Acids & Section 2 Strength of Acids & Bases Bases slides 19-29slides 19-29

Section 3 Salts Section 3 Salts slides 30-46slides 30-46

1- Acids and Bases1- Acids and Bases

What You’ll Learn:What You’ll Learn: How acids & bases are similar & How acids & bases are similar &

differentdifferent Formulas and uses of common Formulas and uses of common

acids and basesacids and bases

AcidsAcids

An An acid acid is a substance that is a substance that produces hydrogen ions, Hproduces hydrogen ions, H+, +, in a in a water solution. water solution.

The ability to produce these ions The ability to produce these ions that gives acids their characteristic that gives acids their characteristic properties.properties.

A A hydronium ion,hydronium ion, H H33OO++ , is a , is a combination of an Hcombination of an H+ + ion & a water ion & a water molecule.molecule.

Properties of AcidsProperties of Acids

Taste sour, BUT DON’T TASTETaste sour, BUT DON’T TASTE Some can burn youSome can burn you Are corrosive, can eat away metalAre corrosive, can eat away metal Cause indicators to change colorCause indicators to change color

IndicatorIndicator

An organic compound that An organic compound that changes color in acid and base.changes color in acid and base.

Litmus paper is an indicator that Litmus paper is an indicator that turns red in acids.turns red in acids.

What are some What are some common acids?common acids? Many foods contain acids:Many foods contain acids:

– Citrus fruits,Citrus fruits,– Lactic acid in yogurt & buttermilkLactic acid in yogurt & buttermilk– Pickled foods contain vinegar or Pickled foods contain vinegar or

acetic acidacetic acid– Your stomach contains hydrochloric Your stomach contains hydrochloric

acid to help digest foodacid to help digest food

Common Acids & Their Common Acids & Their UsesUsesNameName UseUse Other InfoOther Info

Acetic AcidAcetic Acid Food preservation Food preservation & preparation& preparation

In solution w/ In solution w/ water= vinegarwater= vinegar

AcetylsalicyliAcetylsalicylicc

Pain & fever reliefPain & fever relief Known as aspirinKnown as aspirin

Ascorbic Ascorbic acidacid

Antioxidant, Antioxidant, vitaminvitamin

Vitamin CVitamin C

Carbonic Carbonic acidacid

Carbonated Carbonated drinksdrinks

Cave formation, Cave formation, acid rainacid rain

HydrochloricHydrochloric Gastric juice; Gastric juice; steel cleanersteel cleaner

Muriatic acidMuriatic acid

Nitric acidNitric acid To make To make fertilizersfertilizers

Colorless yet Colorless yet yellows when yellows when light exposedlight exposed

Phosphoric Phosphoric To make detergents, To make detergents, fertilizers & other fertilizers & other chemicalschemicals

Slightly sour taste; Slightly sour taste; detergents cause detergents cause water pollutionwater pollution

Sulfuric acidSulfuric acid Car batteries, to make Car batteries, to make fertilizers, etc.fertilizers, etc.

Dehydrating agent, Dehydrating agent, causes burnscauses burns

BasesBases

A A base base is any substance that forms is any substance that forms hydroxide ions, OHhydroxide ions, OH--, in a water , in a water solution. A base is also any solution. A base is also any substance that accepts Hsubstance that accepts H+ + ions from ions from acids.acids.

Unlike acids, not many foods are Unlike acids, not many foods are bases- egg whites, baking powder & bases- egg whites, baking powder & medicinal antacids.medicinal antacids.

Soap is basic; characteristic slipperySoap is basic; characteristic slippery

BasesBases

Many cleaning products contain Many cleaning products contain bases.bases.

Used in industry- NaOH used to Used in industry- NaOH used to separate cellulose fibers from separate cellulose fibers from wood pulp to make paper.wood pulp to make paper.

What are the What are the properties of bases?properties of bases? Bases are the opposite of acids.Bases are the opposite of acids. When not dissolved in water, When not dissolved in water,

many are solids in the form of many are solids in the form of crystals.crystals.

In solution, they feel slippery and In solution, they feel slippery and taste bitter.taste bitter.

Like strong acids, strong bases are Like strong acids, strong bases are corrosive & can burn you.corrosive & can burn you.

What are the What are the properties of bases?properties of bases? NEVER taste or touch a substance NEVER taste or touch a substance

to see if it’s basic.to see if it’s basic. Bases also cause indicators to Bases also cause indicators to

change color. Litmus paper is an change color. Litmus paper is an indicator that turns blue in bases.indicator that turns blue in bases.

What are some What are some common bases?common bases?

Aluminum Aluminum hydroxidehydroxide

Color-fast fabrics, Color-fast fabrics, antacid, water antacid, water purificationpurification

Sticky gel that Sticky gel that collects suspended collects suspended clay & dirt particles clay & dirt particles on its surfaceon its surface

Calcium Calcium hydroxidehydroxide

Leather-making, Leather-making, mortar & plaster, mortar & plaster, lessen acidity of soillessen acidity of soil

Called caustic Called caustic limelime

Magnesium Magnesium hydroxidehydroxide

Laxative, antacidLaxative, antacid Called milk of Called milk of magnesia when in magnesia when in waterwater

Sodium Sodium hydroxidehydroxide

To make soap, oven To make soap, oven cleaner, drain cleaner, drain cleaner, textiles, cleaner, textiles, paperpaper

Called lye & caustic Called lye & caustic soda, exothermic soda, exothermic when added to when added to waterwater

AmmoniaAmmonia Cleaners, fertilizer, Cleaners, fertilizer, to make rayon & to make rayon & nylonnylon

Irritating odor that Irritating odor that damages nasal damages nasal passages & lungspassages & lungs

Solutions of Acids & Solutions of Acids & BasesBases Water is the main solvent for acid Water is the main solvent for acid

and base products because water and base products because water has polarity.has polarity.

Remember, polarity means a Remember, polarity means a molecule has a slightly negative molecule has a slightly negative end & a slightly positive end.end & a slightly positive end.

What happens when What happens when acids dissolve in acids dissolve in water?water? The negative ends of nearby The negative ends of nearby

water molecules attract the water molecules attract the positive hydrogen in the acid.positive hydrogen in the acid.

The acid separates into ions, The acid separates into ions, which is called dissociation.which is called dissociation.

The HThe H+ + ions combine with the ions combine with the water molecules to form water molecules to form hydronium ions (Hhydronium ions (H33OO++).).

What happens when What happens when acids dissolve in acids dissolve in water?water?

+ +

HCl + H2O H30+ + Cl-

What happens when What happens when bases dissolve in bases dissolve in water?water? Bases form hydroxide ions (OHBases form hydroxide ions (OH--) )

in water.in water. Positive ends of nearby water Positive ends of nearby water

molecules attract the hydroxide molecules attract the hydroxide ions in the base which do not ions in the base which do not combine with water molecules.combine with water molecules.

How is ammonia How is ammonia different from other different from other bases?bases? Ammonia is a base that does not Ammonia is a base that does not

contain –OH. In water, ammonia contain –OH. In water, ammonia actually dissociates water molecules actually dissociates water molecules to form an ammonium ion, NHto form an ammonium ion, NH44

++.. You should NEVER use products You should NEVER use products

containing ammonia with other containing ammonia with other cleaners containing chlorine. They cleaners containing chlorine. They react producing toxic gases.react producing toxic gases.

2- Strength of Acids 2- Strength of Acids and Basesand Bases What You’ll Learn:What You’ll Learn: What makes acids & bases strong What makes acids & bases strong

or weakor weak How strength and concentration How strength and concentration

are alike and different are alike and different

Strong & Weak Acids & Strong & Weak Acids & BasesBases The strength of an acid or a base The strength of an acid or a base

depends on how many acid molecules depends on how many acid molecules dissociate into ions in water.dissociate into ions in water.

In a In a strong acid strong acid almost all acid almost all acid molecules dissociate in water. molecules dissociate in water. Examples include hydrochloric acid Examples include hydrochloric acid (HCl), nitric acid (HNO(HCl), nitric acid (HNO33), and sulfuric ), and sulfuric acid (Hacid (H22SOSO44).).

Strong & Weak Acids & Strong & Weak Acids & BasesBases In a In a weak acid weak acid

only a small only a small number of acid number of acid molecules molecules dissociate in dissociate in water. Examples water. Examples include acetic include acetic acid (CHacid (CH33COOH), COOH), and carbonic acid and carbonic acid (H(H22COCO33).).

Acetic acid is used to preserve pickles.

How do you write How do you write chemical equations for chemical equations for acid dissociation?acid dissociation? An equation for the dissociation of a An equation for the dissociation of a

strong acid uses a single arrow hat strong acid uses a single arrow hat points toward the ions that form.points toward the ions that form.

HCl HCl (g) (g) + H+ H22OO(l)(l) H H33OO++(aq)(aq) + Cl+ Cl--(aq)(aq) In weak acids an equation uses In weak acids an equation uses

double arrows pointing in opposite double arrows pointing in opposite directions.directions.

CHCH33COOHCOOH(l)(l)+H+H22 HH33OO(aq)(aq)+CH+CH33COOCOO--

How are strength and How are strength and concentration concentration described?described? Strong & weakStrong & weak refer to how easy it is refer to how easy it is

for the acid or base to dissociate in for the acid or base to dissociate in solution. Strong acids & bases solution. Strong acids & bases dissociate completely while weak dissociate completely while weak acids & bases only partially acids & bases only partially dissociate.dissociate.

Dilute & concentratedDilute & concentrated tell how much tell how much acid or base is dissolved in the acid or base is dissolved in the solution (few or many).solution (few or many).

pH of a SolutionpH of a Solution

TheThe pH pH of a solution is a measure of a solution is a measure of the concentration of Hof the concentration of H++ ions in ions in the solution.the solution.

The scale ranges from 0 to 14 The scale ranges from 0 to 14 with the greater the with the greater the concentration of Hconcentration of H++ ions, the ions, the lower on the scale and the more lower on the scale and the more acidic it is.acidic it is.

pH scalepH scale

pH scalepH scale

Solns with a pH lower than 7 are Solns with a pH lower than 7 are acidic or with a pH greater than 7 are acidic or with a pH greater than 7 are basic. basic.

Solns with a pH of 7 are called neutral Solns with a pH of 7 are called neutral & have equal conc. of H& have equal conc. of H+ + & OH& OH-- ions. ions. Pure water at 25Pure water at 25°C has a pH of 7.°C has a pH of 7.

Universal indicator paper changes Universal indicator paper changes color when ions are present. A pH color when ions are present. A pH meter uses electrodes to determine meter uses electrodes to determine pH.pH.

pH scalepH scale

Why is pH of blood Why is pH of blood important?important? The pH of your blood must remain The pH of your blood must remain

between 7.0 & 7.8 in order for between 7.0 & 7.8 in order for enzymes to work. Enzymes are enzymes to work. Enzymes are protein molecules that act as protein molecules that act as catalysts for many of your body’s catalysts for many of your body’s reactions.reactions.

Buffers Buffers are solutions containing ions are solutions containing ions that react with acids or bases to that react with acids or bases to decrease their effects on pH.decrease their effects on pH.

Why is pH of blood Why is pH of blood important?important? Buffers Buffers are solutions containing are solutions containing

ions that react with acids or bases ions that react with acids or bases to decrease their effects on pH.to decrease their effects on pH.

Buffers help your blood stay at an Buffers help your blood stay at an almost constant pH of 7.4. One almost constant pH of 7.4. One buffer system in the blood buffer system in the blood involves bicarbonate ions, HCOinvolves bicarbonate ions, HCO33

--..

3- Salts3- Salts

What You’ll Learn:What You’ll Learn: IdentifyIdentify a neutralization reactiona neutralization reaction About salt and how it formsAbout salt and how it forms About soaps and detergentsAbout soaps and detergents

NeutralizationNeutralization

Neutralization Neutralization is a chemical is a chemical reaction between an acid & a reaction between an acid & a base that happens in a water base that happens in a water solution. NaOH neutralizes HCl. solution. NaOH neutralizes HCl. Hydronium ions from the acid Hydronium ions from the acid combine with OHcombine with OH-- from the base from the base producing neutral water.producing neutral water.

HCl + NaHCOHCl + NaHCO33 2H 2H22OO

NeutralizationNeutralization

Antacids are medicines that Antacids are medicines that contain bases or other contain bases or other compounds that neutralize the compounds that neutralize the HCl in your stomach. One of HCl in your stomach. One of these antacids is sodium these antacids is sodium bicarbonate- NaHCObicarbonate- NaHCO33..

HCl + NAHCOHCl + NAHCO33NaCl + CONaCl + CO22+H+H22OO

How is salt formed?How is salt formed?

HCl is neutralized by NaOH but HCl is neutralized by NaOH but only half the ions are shown. The only half the ions are shown. The other ions react to form a salt. A other ions react to form a salt. A salt salt is a compound formed when is a compound formed when the negative ions from an acid the negative ions from an acid combine with the positive ions combine with the positive ions from a base.from a base.

NaNa+++ Cl+ Cl-- NaCl NaCl

How do acid-base How do acid-base equations look?equations look? Acid + base Acid + base salt + water salt + water The equation for the reaction The equation for the reaction

between HCl and NaOH is:between HCl and NaOH is: HCl + NaOH HCl + NaOH NaCl + H NaCl + H22OO

SaltsSalts

Salt is necessary for many Salt is necessary for many organisms. organisms.

Most salts are made of a positive Most salts are made of a positive metal ion & a negative ion such metal ion & a negative ion such as Cl or COas Cl or CO33. .

Ammonium salts contain NHAmmonium salts contain NH44 instead of a metal.instead of a metal.

Some Common SaltsSome Common SaltsName, Name,

FormulaFormulaCommon Common

NameNameUsesUses

Sodium Sodium chloride, chloride, NaClNaCl

SaltSalt Food, Food, making making chemicalschemicals

Sodium Sodium hydrogen hydrogen carboncarbon

Sodium Sodium bicarbonate bicarbonate baking sodabaking soda

Food, Food, antacidsantacids

Potassium Potassium nitrate, KNOnitrate, KNO33

saltpetersaltpeter fertilizersfertilizers

Ammonium Ammonium chloridechloride

Sal Sal ammoniacammoniac

Dry-cell Dry-cell batteriesbatteries

TitrationTitration In In titration,titration, a solution of known a solution of known

concentration is used to find the concentration is used to find the concentration of another solution.concentration of another solution.

Measure the volume of the solution Measure the volume of the solution of unknown concentration. Add a of unknown concentration. Add a few drops of phenolphthalein, a few drops of phenolphthalein, a colorless indicator that turns pink colorless indicator that turns pink in a base & stays pink when the in a base & stays pink when the acid is neutralized.acid is neutralized.

TitrationTitration Since the unknown is an acid, slowly Since the unknown is an acid, slowly

& carefully add a base solution of & carefully add a base solution of known concentration drop by drop known concentration drop by drop until one drop turns the solution pink until one drop turns the solution pink and the color stays. The completed and the color stays. The completed titration is the endpoint. The acid is titration is the endpoint. The acid is neutralized. Use the volume of the neutralized. Use the volume of the base that was added to calculate the base that was added to calculate the concentration of the acid solution.concentration of the acid solution.

What are indicators?What are indicators? Many natural substances are acid-Many natural substances are acid-

base indicators. The indicator litmus base indicators. The indicator litmus comes from a combination of a comes from a combination of a fungus and a algae called lichen. fungus and a algae called lichen. The flowers of the hydrangea plant The flowers of the hydrangea plant are indicators, pink in basic soil & are indicators, pink in basic soil & blue in acidic soil. Red cabbage blue in acidic soil. Red cabbage juice is also an indicator- deep red juice is also an indicator- deep red at pH 1, lavender at pH 7, & yellow-at pH 1, lavender at pH 7, & yellow-green at pH 10.green at pH 10.

Soaps and DetergentsSoaps and Detergents

SoapsSoaps are organic salts with a are organic salts with a nonpolar organic chain of carbon nonpolar organic chain of carbon atoms on one end of the atoms on one end of the molecule. On the other end, they molecule. On the other end, they have either a Na or a K salt of a have either a Na or a K salt of a carboxylic acid-COOH group.carboxylic acid-COOH group.

SoapSoap

The long nonpolar The long nonpolar tail mixes with oils tail mixes with oils and dirt while the and dirt while the polar head polar head attracts water attracts water molecules.molecules.

This attraction This attraction helps wash away helps wash away dirt and oil linked dirt and oil linked to the soapto the soap

What are commercial What are commercial soaps & detergents?soaps & detergents? A long-chain fatty acid from natural A long-chain fatty acid from natural

oils like canola, palm and coconut is oils like canola, palm and coconut is reacted with sodium or potassium reacted with sodium or potassium hydroxide to make simple soaps.hydroxide to make simple soaps.

Sometimes tap water contains Sometimes tap water contains metal ions (Ca, Mg, & Fe) that react metal ions (Ca, Mg, & Fe) that react with soap replacing the Na or K ions with soap replacing the Na or K ions making soap insoluble in water. making soap insoluble in water. Ions separate out of solution in the Ions separate out of solution in the form of soap scum.form of soap scum.

What are commercial What are commercial soaps & detergents?soaps & detergents? Detergents are like soap except Detergents are like soap except

they are made with petroleum they are made with petroleum molecules instead of from natural molecules instead of from natural fatty acids with a sulfonic group at fatty acids with a sulfonic group at the end instead of a carboxylic acid the end instead of a carboxylic acid group. Detergents leave less soap group. Detergents leave less soap scum, increase sudsing & improve scum, increase sudsing & improve cleaning in hard water. Can cause cleaning in hard water. Can cause foam in water treatment plants & in foam in water treatment plants & in streams.streams.

Versatile EstersVersatile Esters Esters are organic versions of Esters are organic versions of

salts, made from acids with water salts, made from acids with water as a product of the reaction.as a product of the reaction.

Instead of reacting with bases, Instead of reacting with bases, acids react with alcohols that have acids react with alcohols that have a hydroxyl group to produce a hydroxyl group to produce esters.esters.

Esters are used to make soap, Esters are used to make soap, flavoring, perfumes & fibers for flavoring, perfumes & fibers for clothing.clothing.

How are esters used How are esters used for flavors?for flavors? Many drinks taste like real fruit Many drinks taste like real fruit

but do not contain any fruit, only but do not contain any fruit, only artificial flavors such as artificial flavors such as pineapple, banana, orange, pineapple, banana, orange, apricot, & apple. apricot, & apple.

The reaction to prepare esters The reaction to prepare esters involves removing a molecule of involves removing a molecule of water from an acid & an alcohol.water from an acid & an alcohol.

What are polyesters?What are polyesters?

Synthetic fibers resulting from a Synthetic fibers resulting from a reaction between an organic acid reaction between an organic acid and alcohol produces long, nonpolar and alcohol produces long, nonpolar chains of many, or poly, esters. chains of many, or poly, esters.

These fibers may be used alone or These fibers may be used alone or woven or knitted with natural fibers woven or knitted with natural fibers to make strong, water repellant, & to make strong, water repellant, & colorfast fabric.colorfast fabric.