ACIDS AND BASESACIDS AND BASES

Acids found around the Acids found around the househouse

• Citric - all citrus fruitCitric - all citrus fruit• Acetic acid – vinegarAcetic acid – vinegar• Carbonic – sodaCarbonic – soda• Tannic – teaTannic – tea• Lactic- milk, yogurt Lactic- milk, yogurt • Sulfuric – car batterySulfuric – car battery• Hydrochloric – metal and masonry Hydrochloric – metal and masonry

cleaningcleaning

• Organic acids are those made by an Organic acids are those made by an organismorganism

• Mineral acids or inorganic are those Mineral acids or inorganic are those that can be made directly at the lab that can be made directly at the lab bench, also referred to as industrial bench, also referred to as industrial acids.acids.

3 Common Industrial 3 Common Industrial AcidAcid

1.1. Sulfuric ( HSulfuric ( H22SOSO4 4 ) used in most ) used in most manufacturing manufacturing

Conc 98 % , specific gravity 1.84g/mlConc 98 % , specific gravity 1.84g/ml

dilute = 1 part acid to 5 parts waterdilute = 1 part acid to 5 parts water

2. Hydrochloric (HCl ) masonry and metal 2. Hydrochloric (HCl ) masonry and metal cleaning .cleaning .

Conc 36 % , specific gravity 1.19 g/mlConc 36 % , specific gravity 1.19 g/ml

dilute = 1 part acid to 4 parts water. dilute = 1 part acid to 4 parts water.

3 Nitric acid ( HNO3 Nitric acid ( HNO33 ) Tanning ) Tanning leather, making fertilizer and leather, making fertilizer and explosivesexplosives

Conc 70 % Specific gravity 1.42 Conc 70 % Specific gravity 1.42 g/mlg/ml

dilute = 1 part acid to 3 parts dilute = 1 part acid to 3 parts waterwater

Demo the three.Demo the three.

Acids BasesAcids Bases

• Have a sour tasteHave a sour taste• Affect indicatorsAffect indicators blue litmus turns redblue litmus turns red

• Acids neutralize basesAcids neutralize bases to make a salt + to make a salt + waterwater

• Are electrolytes Are electrolytes • Many React with Many React with

metals to release metals to release hydrogenhydrogen

• Have a bitter tasteHave a bitter taste• Affect indicatorsAffect indicators red litmus turns red litmus turns

blueblue B-B base = blueB-B base = blue• Bases neutralize Bases neutralize

acidsacids to make a salt + to make a salt +

waterwater• Are electrolytesAre electrolytes• Feel slipperyFeel slippery

Common bases around Common bases around the housethe house

• Milk of magnesa Mg(OH)Milk of magnesa Mg(OH)22

• Draino NaOHDraino NaOH• House hold Ammonia NHHouse hold Ammonia NH44OHOH• Rolaids Mg(OH)Rolaids Mg(OH)2 2 / CaCO/ CaCO33

• Tums Al(OH)Tums Al(OH)33 ? ? • Milanta , peptobismo Milanta , peptobismo • Lime CaO for the lawn. Plus HLime CaO for the lawn. Plus H22O O

makes Ca(OH)makes Ca(OH)22

Arrhenius’s Theory of Arrhenius’s Theory of ionizationionization

H+H+•

HH22O + HO + H22O → HO → H33OO++ + OH + OH--

• Water + water yields Hydronium Water + water yields Hydronium ion + hydroxide ionion + hydroxide ion

• If HIf H22O loses an HO loses an H++ what do you have left? what do you have left?

an OHan OH- - ion ion

• You get 1.0 x 10You get 1.0 x 10-7-7 H H33OO++ and 1.0 and 1.0 X 10X 10-7-7 OH OH-- for every liter of pure for every liter of pure water.water.

• Notice that the hydronium and Notice that the hydronium and hydroxide ion concentrations are hydroxide ion concentrations are equal, that’s a neutral solution.equal, that’s a neutral solution.

• When HWhen H33OO++ > OH > OH- - its an acid its an acid

• When OHWhen OH- - > H > H33OO++ it’s a base it’s a base

• The pH scale is a system to express the The pH scale is a system to express the

“ “ power of hydronium” .power of hydronium” .

The pH of a neutral solution is 7The pH of a neutral solution is 7

The HThe H33OO++ concentration is 1.0 X 10 concentration is 1.0 X 10 -7 -7

When pH is 3, When pH is 3,

[H[H33OO++ ] = 1.0 x 10 ] = 1.0 x 10 -3-3

When pH is 9When pH is 9

[H[H33OO++ ] is 1.0 x 10 ] is 1.0 x 10 -9-9

[ ] means concentration in moles/liter [ ] means concentration in moles/liter isis

• This true so long as the conc is This true so long as the conc is 1.01.0 times the exponent.times the exponent.

• If its not, its math time.If its not, its math time.

• pH = -log( HpH = -log( H33OO++ ) )

• What is the pH when[ HWhat is the pH when[ H33OO++ ] is 3.4 x ] is 3.4 x 1010-5-5 ? ?

• - log 3.4 2- log 3.4 2ndnd ee – 5 ) enter ee – 5 ) enter• You get 4.468521 or 4.47 as the pHYou get 4.468521 or 4.47 as the pH

• Other directionOther direction

• pH = 4.47 what is the [HpH = 4.47 what is the [H33OO++] ?] ?

• Antilog ( -ph ) = [ HAntilog ( -ph ) = [ H33OO++ ] ]

• 22ndnd log - 4.47 ) enter log - 4.47 ) enter• You get 3.4 x 10You get 3.4 x 10-5-5

Back to ArrheniusBack to Arrhenius

• In a neutral solution [ HIn a neutral solution [ H33OO++ ] = ] = [ OH[ OH-- ] ]

• Because both equal 1.0 x 10Because both equal 1.0 x 10-7-7

• [ H[ H33OO++ ] X [ OH ] X [ OH- - ] = 1.0 x 10] = 1.0 x 10-14-14

• Which is a constant, so given either Which is a constant, so given either the [Hthe [H33OO++] or the [OH] or the [OH-- ] you can ] you can solve for the other.solve for the other.

• [ H[ H33OO++ ] = ] = 1.0 x 101.0 x 10-14 -14

[ OH[ OH-- ] ]

[ OH[ OH-- ] = ] = 1.0 x 101.0 x 10-14-14

[ H[ H33OO++ ] ]

pOH = -Log[OH]pOH = -Log[OH]

pH + pOH = 14 pH + pOH = 14

if you know either the pH or the pOH, if you know either the pH or the pOH, just subtract the one you have from just subtract the one you have from 14 and you have the other one.14 and you have the other one.

• Bronsted and Lowery Bronsted and Lowery

Defined an acid as a proton donor and Defined an acid as a proton donor and a base as a proton accepter. a base as a proton accepter.

There for any substance that contains There for any substance that contains ionizable hydrogen is an acid. ionizable hydrogen is an acid.

And any negative ion can be a base.And any negative ion can be a base.

HCl + HHCl + H22O → HO → H33OO++ + Cl + Cl- -

in the forward reaction the HCl is in the forward reaction the HCl is the acid and the water is the base. the acid and the water is the base.

Short form Short form

HCl → HHCl → H++ + Cl + Cl- - it is assumed it is assumed you know the water is required.you know the water is required.

Conjugate acid base Conjugate acid base pairspairs

A conjugate base is a base that is A conjugate base is a base that is produced when an acid gives up a produced when an acid gives up a proton. proton.

HH22SOSO44 → HSO → HSO44-- + H + H++

In this case the HSOIn this case the HSO44-- is the base is the base

produced when the Hproduced when the H22SOSO44 gave up the gave up the HH++ because the bisulfate ion has a because the bisulfate ion has a negative charge it is a base according negative charge it is a base according to Bronsted/Loweryto Bronsted/Lowery

The only difference between a The only difference between a conjugate acid/base pair is one conjugate acid/base pair is one stinking hydrogen.stinking hydrogen.

The acid has it and the base does not. The acid has it and the base does not.

So to determine the conjugate base all So to determine the conjugate base all you do is subtract one H from the you do is subtract one H from the acid and make the resulting ion (-) acid and make the resulting ion (-)

Do some practice problems

Monoprotic acids only have one ionizable Monoprotic acids only have one ionizable Hydrogen , ionizable means that the H Hydrogen , ionizable means that the H can be seperated from the rest of the can be seperated from the rest of the formula. HCl, HNOformula. HCl, HNO33, H C, H C22HH33OO22

Diprotic acids have two ionizable hydrogens

H2SO4 and H2CO3

Triprotic acids have three. H3PO4 Write some ionization equations

Amphprotic substances are those that can Amphprotic substances are those that can act as either an acid or a base.act as either an acid or a base.

The HSOThe HSO44-- ion has an ionizable Hydrogen ion has an ionizable Hydrogen

and a negative charge. So it can give up and a negative charge. So it can give up the H to act as an acid or since its negative the H to act as an acid or since its negative it can accept an H to act as a base. it can accept an H to act as a base.

These substances are commonly called These substances are commonly called Buffers.Buffers.

Why? Why?

TitrationTitration

• Acid buret Base buretAcid buret Base buret

The Process of reacting a solution of known concentration with one of unknown concentration to determine The concentration of the unknown solution.

Titration uses knowledge of balanced Titration uses knowledge of balanced equations and mass/mass problems to equations and mass/mass problems to determine the concentration of an determine the concentration of an unknown solution.unknown solution.

If you know the moles of one reactant, it If you know the moles of one reactant, it is possible to calculate the moles of the is possible to calculate the moles of the other from the balanced equation. other from the balanced equation. Then if volume of liquid is also known, Then if volume of liquid is also known, molarity can be determined.molarity can be determined.

This sounds hard, but there is an easy This sounds hard, but there is an easy way to do it if we convert molarity to way to do it if we convert molarity to normality.normality.

Normality / + charge = molarity Normality / + charge = molarity

So So

Molarity x ( + charge ) = normalityMolarity x ( + charge ) = normality

.4M H.4M H22SOSO4 4 .4M x +2 (from the two .4M x +2 (from the two H’s)=.8NH’s)=.8N

Titration equationTitration equation

Normaliy of acid x volume of acid = Normaliy of acid x volume of acid = Normality of base x volume of base.Normality of base x volume of base.

NNaaVVaa = N = NbbVVb b

easy math plug in the three knowns easy math plug in the three knowns and solve for the missing one.and solve for the missing one.

If necessary convert back to molarityIf necessary convert back to molarity

Titration curve and Titration curve and equivalence pointequivalence point

The equivalence point is the point The equivalence point is the point where you have added an equivalent where you have added an equivalent amount of base to the acid which amount of base to the acid which will just neutralize the acid. The will just neutralize the acid. The indicator will change color and your indicator will change color and your done. ( the end point)done. ( the end point)

Strong and weak acidsStrong and weak acids

HCl → HHCl → H++ + Cl + Cl- -

100 molecules → 100 ions + 100 ions 100 molecules → 100 ions + 100 ions

Every molecule of acid ionizes, that a strong acid.Every molecule of acid ionizes, that a strong acid.

HCHC22HH33OO22 → H → H+ + + C + C22HH33OO22--

100 molecules → 10 ions + 10 ions + 100 molecules → 10 ions + 10 ions + 90 HC90 HC22HH33OO22 that did nothing , that’s a that did nothing , that’s a weak acid.weak acid.

Only 10 % of the acid did any thing.Only 10 % of the acid did any thing.

Strong and weak bases do the same Strong and weak bases do the same thing. thing.

Acid Anhydrides Acid Anhydrides

Non metallic oxides that react with Non metallic oxides that react with water to form and acid. That’s what water to form and acid. That’s what causes acid rain.causes acid rain.

SOSO22 + H + H22O → HO → H22SOSO33 sulfurous acid sulfurous acid

COCO22 + H + H22O → HO → H22COCO33 carbonic acid carbonic acid

Basic anhydrideBasic anhydride

Is a metallic oxide that reacts with Is a metallic oxide that reacts with water to form a base. water to form a base.

CaO + HCaO + H22O → Ca(OH)O → Ca(OH)2 2

Any of the group I or II elements do Any of the group I or II elements do the same thing. the same thing.

Naming acids Naming acids

• Binary acids , contain only two Binary acids , contain only two elements elements

• HCl Hydro-chloric acidHCl Hydro-chloric acid• HF Hydro-floric acidHF Hydro-floric acid• HBr Hydro-bromic acidHBr Hydro-bromic acid• HI Hydro-iodic acidHI Hydro-iodic acid

Ternary or Oxy acidsTernary or Oxy acids

• Contain Hydrogen , oxygen and a third Contain Hydrogen , oxygen and a third element.element.

• per = 1 more (O) HClOper = 1 more (O) HClO44 perperchlorchloricic acidacid

• Root acid HCLORoot acid HCLO33 chlor chloricic acid acid

• 1 less (O) HClO1 less (O) HClO2 2 chlor chlorousous acid acid

• 2 Less (O) HClO 2 Less (O) HClO hypohypochlorchlorousous

Other Root acids Other Root acids

• If you understand the previous system, If you understand the previous system, and Know the names and formulas of the and Know the names and formulas of the following root acids, (memorize them) following root acids, (memorize them) naming oxy-acids is easy. naming oxy-acids is easy.

• HH22SOSO44 - sulfuric acid - sulfuric acid

• HNOHNO33 - nitric acid - nitric acid

• HH22COCO33 - carbonic acid - carbonic acid

• HH33POPO44 - phosphoric acid - phosphoric acid

• HCLOHCLO33 - chloric acid - chloric acid

Making acid solutions from Making acid solutions from the concentrated liquidthe concentrated liquid

• Question : How much concentrated sulfuric Question : How much concentrated sulfuric acid is needed to make 400ml of .3M acid is needed to make 400ml of .3M HH22SOSO44 ? ?

• Using molarity x fw x Liters = grams Using molarity x fw x Liters = grams

• .3 M x 98 x .400 L = 11.7 grams H.3 M x 98 x .400 L = 11.7 grams H22SOSO4 4

so how many so how many mlml of the conc liquid do we of the conc liquid do we need?need?

Concentrated HConcentrated H22SOSO44 is 98 % acid and has a is 98 % acid and has a specific gravity of 1.84g/mlspecific gravity of 1.84g/ml

• That means each ml of the acid has a mass of 1.84 That means each ml of the acid has a mass of 1.84 grams. grams.

1.84 gram1.84 gram x .98x .98 1.80 grams dry weight per ml 1.80 grams dry weight per ml From above we needed 11.7 grams dry weight From above we needed 11.7 grams dry weight

11.7 grams x 11.7 grams x 1 ml1 ml = 6.6 ml of conc H = 6.6 ml of conc H22SOSO44

1.80 grams 1.80 grams

Place 6.6 ml of conc acid in a graduated cylinder and Place 6.6 ml of conc acid in a graduated cylinder and add enough water to bring the total volume to 400ml add enough water to bring the total volume to 400ml and you are done.and you are done.

I forgot about Lewis I forgot about Lewis acidsacids

Work in progressWork in progressnot done yetnot done yet

• ..