Acids and Bases in all Different Places

I. Properties of Acids

• A. Molecular substances which ionize when added to water to form hydronium (H3O+1) ions all acids are electrolytes

• B. React with active metals to form H2(g)

– 1. _ Mg(s) + _ HCl(aq) – 2. _ Zn(s) + _ HCl(aq) – 3. _ Cu(s) + _ HCl(aq)

I. Properties of Acids

• C. Acids affect the colors of indicators– Universal Indicator – Phenolphthalein

• D. Acids neutralize bases• E. Dilute acids taste sour think citric acid

and ascorbic acid (Vitamin C) • **SAFETY TIP: Acids release tremendous

amounts of heat when you dilute them – (esp. H2SO4) ALWAYS ADD ACID TO WATER

II. Naming Acids• treated as an ionic compound with H+1 (hydrogen ion) as

cation• negative ion can be nonmetal (binary acid) or polyatomic

anion (ternary acid) – A) Binary acids – acids that contain a negative ion ending in “-

ide”• 1) Formula Name

– use prefix: hydro-– use root of anion’s name– use suffix: -ic

• a) HCl b) HBr c) HF• hydrochloric acid hydrobromic acid hydrofluoric acid

II. Naming Acids

• 2) Name Formula– follow above rules in reverse– be sure to balance charges

• a) hydroiodic acid b) hydrosulfuric acid

• HI H2S

II. Naming Acids

• B) Ternary acids– DO NOT BEGIN WITH “hydro-“!!!!!!!– use name of polyatomic ion and switch its ending:

• NOTE: sulfur stays “sulfur-” + ending,

phosphorus stays “phosphor-” + ending

Ion Name Ending Acid Name ending

-ide Hydro- ____ -ic acid

-ate _________ -ic acid

II. Naming Acids• 1) Formula Name

– a) H2CO3

• CO3 carbonATE carbonic acid

– b) H2SO4

• SO4 sulfATE sulfuric acid

• 2) Name Formula– a) acetic acid

• acetIC acetATE HC2H3O2

– b) phosphoric acid• phosphorIC phosphATE H3PO4

– c) nitric acid• nitrIC nitrATE HNO3

** some acids are stronger than others:Acid Conjugate Base Ka Acid Conjugate

BaseKa

HI H+1 + I-1 very large H2CO3 H+1 + HCO3-1 4.3 x 10-7

HBr H+1 + Br-1 very large HSO3-1 H+1 + SO3

-2 1.1 x 10-7

HCl H+1 + Cl-1 very large H2S H+1 + HS-1 9.5 x 10-8

HNO3 H+1 + NO3-1 very large H2PO4

-1 H+1 + HPO4-2 6.2 x 10-8

H2SO4 H+1 + HSO4-1 large NH4

+1 H+1 + NH3 5.7 x 10-10

H2SO3 H+1 + HSO3-1 1.5 x 10-2 HCO3

-1 H+1 + CO3-2 5.6 x 10-11

HSO4-1 H+1 + SO4

-2 1.2 x 10-2 HPO4-2 H+1 + PO4

-3 2.2 x 10-13

H3PO4 H+1 + H2PO4-2 7.5 x 10-3 HS-1 H+1 + S-2 1.3 x 10-14

HF H+1 + F-1 6.3 x 10-4 H2O H+1 + OH-1 1.0 x 10-14

HNO2 H+1 + NO-1 5.6 x 10-4 OH-1 H+1 + O-2 < 10-36

HC2H3O2 H+1 + C2H3O2-1 1.8 x 10-5

Rank the following acids from weakest to strongest: sulfuric acid, carbonic acid, hydrochloric acid, hydrofluoric acid, acetic acid

H2CO3 , HC2H3O2 , HF, H2SO4 , HCl

III. Bases - ionic substance which dissociates to form hydroxide (OH-1) ions in water

* examples: lye (NaOH) , lime (Ca(OH)2) , milk of magnesia (Mg(OH)2)

• Naming Review. Name (or give the formula for) the following bases:• 1. NaOH• sodium hydroxide• 2. Mg(OH)2

• magnesium hydroxide• 3. aluminum hydroxide• Al(OH)3

• 4. ammonium hydroxide• NH4OH

IV. Properties of Bases - often referred to as caustic or alkaline substances

• A. Bases are electrolytes - dissociate in water to form OH-.

• B. Bases affect the colors of indicators.– Universal Indicator PURPLE– Phenolphthalein MAGENTA

• C. Bases neutralize acids.• D. Water solutions are bitter and slippery.• E. Emulsify fats and oils this is why they are

useful in soap

V. Salt – any ionic compound that does not contain hydroxide (OH-1)

• * all are good electrolytes

formed by a neutralization reactionAcid + Base Salt + Water

• 1) _____ HCl(aq) + _____ NaOH(aq)

• 2) _____ H2SO4(aq) + ____ KOH(aq)

• 3) ____ HBr(aq) + _____ Ca(OH)2(aq)

• 4) _____ HC2H3O2(aq) + _____ NaOH(aq)

Acid, Base, Salt, or Neither:

• 1. NaCl 2. KCl 3. KOH 4. SO2 5. NH4C2H3O2

• Salt salt base neither salt • 1. KBr 2. H2SO4 3. HgCl2 4. Al(OH)3 5. HCl• Salt acid salt base acid• 6. KOH 7. CaO 8. K3PO4 9. CO2 10. NH4OH• Base salt salt neither base

VI. pH – a mathematical way of measuring how acidic a solution is

pH Acidity

7 neutral

less than 7 acidic

greater than 7 basic

1 2 3 4 5 6 7 8 9 10 11 12 13

battery

acidlemon juice

vinegar milk sea water

milk of magnesia lye

H+10-1M 10-4M 10-7M 10-10M 10-13M

• It’s a logarithmic scale; that means each step is worth 10– lemon juice is 10 times more acidic than vinegar– battery acid is 10 times more acidic than lemon

juice– How many times more acidic is battery acid than

vinegar?

1 2 3 4 5 6 7 8 9 10 11 12 13

battery

acidlemon juice

vinegar milk sea water

milk of magnesia lye

H+10-1M 10-4M 10-7M 10-10M 10-13M

1 2 3 4 5 6 7 8 9 10 11 12 13

battery

acidlemon juice

vinegar milk sea water

milk of magnesia lye

H+10-1M 10-4M 10-7M 10-10M 10-13M

Color scale for Universal Indicator:

pH: 3 5 7 9 11

Red Orange Green Blue Purple

• Which of the solutions above is the most acidic?• Battery acid• 2) Which of the solutions above is the most basic? • Lye• 3) Look at the solutions that your teacher is testing

with universal indicator.– Label each as acidic, basic, or neutral– Estimate the pH based on the color– Rank the substances from most acidic to least acidic

Substance

acidic, basic, neutral pH

1

2

3

4

RANK:

VII. Buffer - a solution which is able to resist major changes in pH

• example: HC2H3O2(aq) H+1(aq) + C2H3O2

-1(aq)

• common-ion effect - by adding a salt with the negative ion (NaC2H3O2, KC2H3O2), we increase the concentration of that ion, therefore:

• add H+1: • the acid will react with the acetate ion to produce molecular

acetic acid, thus “neutralizing” it and keeping the pH the same• add OH-1: • the base will react with the molecular acetic acid to produce

acetate ions, thus “neutralizing” it and keeping the pH the same

BLOODY BUFFERS!!• biological example: carbonic acid/bicarbonate

in blood Hold your Breath!!!• There is a balance between the ions which

acts as a buffer, keeping the pH of the blood right around 7.4. The hemoglobin molecule in red blood cells can only withstand pH extremes of 7.2-7.6

VIII. Acid-Base Indicators - chemicals specifically designed to show specific

colors in acids and different colors in basesIndicator pH Range below pH color above pH color

methyl violet 0.0 – 1.6 yellow bluemethyl yellow 2.9 – 4.0 red yellow

bromophenol blue 3.0 – 4.6 yellow bluemethyl orange 3.2 – 4.4 red yellow

methyl red 4.8 – 6.0 red yellowlitmus 5.5 – 8.0 red blue

bromothymol blue 6.0 – 7.6 yellow bluephenol red 6.6 – 8.0 yellow red

phenolphthalein 8.2 – 10.6 colorless redthymolphthalein 9.4 – 10.6 colorless bluealizarin yellow 10.0 – 12.0 yellow red

IX. Acid-Base Neutralization

• if you have 35 molecules of acid, 35 molecules of base will neutralize it

• equivalence point - when an equivalent amount of OH-1 ions has been added to H+1 ions it’s “neutralized”

H+1 + OH-1 H2O

X. Acid-Base Titration - lab procedure used to determine the concentration of an unknown acid or base solution.

• standard solution – solution whose concentration is known

• unknown solution – solution whose concentration you are trying to determine

• MaVa = MbVb

Titration Problems

• 1) If you begin a titration with 20.0 mL of unknown HCl and titrate it to the equivalence point using 35.6 mL of 0.600 M standard NaOH, what is the concentration of HCl?

• Ma(20.0 mL) = (0.600M)(35.6 mL) Ma = 1.07 M

• 2) If you titrate 65.0 mL of an unknown NH3 solution to the equivalence point with 31.2 mL of a 1.50 M HCl solution, what is the concentration of the ammonia?

• (1.50M)(31.2mL) = Mb(65.0mL) Mb = 0.720 M

Titration Problems

• 1) Ma = ??? Va = 50.0 mL Mb = 1.50 M Vb = 71.3 mL

• Ma(50.0mL) = (1.50M)(71.3mL) Ma = 2.14 M

• 2) What is the concentration of an unknown NaOH solution if you titrate 100.0 mL of it to the equivalence point with 43.5 mL of 6.0 M HCl?

• (6.0M)(43.5mL) = Mb(100.0mL) Mb = 2.6 M

Titration Problems

• 3) What is the concentration of a vinegar (HC2H3O2) solution if you titrate exactly 20 drops of it to the equivalence point with 26 drops of 0.600M NaOH?

• Ma(2θdr) = (0.600M)(26dr) Ma = 0.78 M