ACIDS AND BASES

CHAPTER 15

15.1: WHAT ARE ACIDS AND BASES?

• Objectives:• To name acids and bases.• To write formulas for acids and bases.

RULES FOR NAMING ACIDS

-ide hydro_____ic acid

-ate _____ic acid

-ite _____ous acid

*If a compound begins with hydrogen name it as an acid.

EXAMPLES: NAMING ACIDS

1. HCl• The anion is chloride (Cl-)• For an anion ending in –ide hydro___ic acid• Therefore, the name is hydrochloric acid

EXAMPLES: NAMING ACIDS

1. HCl• The anion is chloride (Cl-)• For an anion ending in –ide hydro___ic acid• Therefore, the name is hydrochloric acid

2. HNO3

• The anion is nitrate (NO3-)

• For an anion ending in –ate ___ic acid• Therefore, the name is nitric acid

EXAMPLES: NAMING ACIDS

1. HCl• The anion is chloride (Cl-)• For an anion ending in –ide hydro___ic acid• Therefore, the name is hydrochloric acid

2. H2SO4

• The anion is sulfate (SO42-)

• For an anion ending in –ate ___ic acid• Therefore, the name is sulfuric acid

3. H2SO3

• The anion sulfite (SO32-)

• For an anion ending in –ite ___ous acid• Therefore, the name acid sulfurous acid

NAME THE FOLLOWING COMPOUND: HBR

A. Bromic acidB. Bromous acidC. Hydrobromic acidD. Hydrobromous acidE. None of the above

NAME THE FOLLOWING COMPOUND: HBR

A. Bromic acidB. Bromous acidC.Hydrobromic acidD. Hydrobromous acidE. None of the above

NAME THE FOLLOWING COMPOUND: H2C2O4

A. Chromic acidB. Oxalate acidC. Dihydrogen dicarbon tetraoxideD. Oxalic acidE. None of the above

NAME THE FOLLOWING COMPOUND: H2C2O4

A. Chromic acidB. Oxalate acidC. Dihydrogen dicarbon tetraoxideD.Oxalic acidE. None of the above

PRACTICE: NAMING ACIDS

1. H2SO3

2. HF3. H3PO4

4. HNO3

5. HI

PRACTICE: NAMING ACIDS

1. H2SO3 : sulfurous acid

2. HF : hyrofluoric acid3. H3PO4 : phosphoric acid

4. HNO3 : nitric acid

5. HI : hydroiodic acid

EXAMPLES: WRITING FORMULAS FOR ACIDS

1. Sulfuric acid

• The anion is sulfate (SO42-)

• The cation is H+

• Criss-cross charges to get H2SO4

2. Carbonic acid

• The anion is carbonate (CO32-)

• The cation is H+

• Criss-cross charges to get H2CO3

H+ SO42-

H+ CO32-

H2SO4

H2CO3

PRACTICE: WRITING FORMULAS FOR ACIDS

1. Hydrochloric acid2. Nitric acid3. Phosphorous acid4. Hydroiodic acid

PRACTICE: WRITING FORMULAS FOR ACIDS

1. Hydrochloric acid: HCl2. Nitric acid: HNO3

3. Phosphorous acid: H3PO3

4. Hydroiodic acid: HI

ACIDS YOU SHOULD KNOW…

Strong Acids Weak AcidsHydrochloric

AcidPhosphoric

AcidSulfuric Acid Acetic AcidNitric Acid

SOME BASES…

Strong Bases Weak Bases

Sodium Hydroxide Ammonia

Potassium Hydroxide Sodium Carbonate

Calcium Hydroxide Potassium Carbonate

Barium Hydroxide

Sodium Phosphate

15.1: WHAT ARE ACIDS AND BASES? CONTINUED

• Objectives:• To list properties of acids and bases.

• To define acid and base.• To identify the acid, base, conjugate acid, and conjugate base in a chemical reaction.

PROPERTIES OF ACIDS

• Taste sour

• Form Hydronium Ions (H3O+)

• Conduct electricity• React with metals

PROPERTIES OF BASES

• Taste bitter• Feel slippery• Generate Hydroxide Ions (OH-)

ACID

• Arrhenius Acid: any substance that, when added to water, increases the hydronium ion (H3O+) concentration

*Note: H+ and H3O+ are used interchangeably

BASE

• Arrhenius Base: generates hydroxide ions (OH-) when dissolved in water

BRØNSTED-LOWRY ACID

• A substance that donates a proton (H+) to another substance.

BRØWNSTED-LOWRY BASE

• A substance that accepts a proton (H+).

CONJUGATE ACID AND CONJUGATE BASE

• Conjugate Acid: an acid that forms when the base gains a H+

• Conjugate Base: the base that forms when an acid loses an H+

IDENTIFY THE CONJUGATE BASE FOR THE FOLLOWING ACIDS:

Acid Conjugate Base

HCl Cl-

H2SO4

H3O+

HSO4-

HOClH2PO4

-

NH4+

IDENTIFY THE CONJUGATE BASE FOR THE FOLLOWING ACIDS:

Acid Conjugate Base

HCl Cl-

H2SO4 HSO4-

H3O+ H2O

HSO4- SO4

2-

HOCl OCl-

H2PO4- HPO4

2-

NH4+ NH3

IDENTIFY THE CONJUGATE ACID FOR THE FOLLOWING BASES:

Conjugate Acid

Base

NH4+ NH3

HCO3-

HS-

Br-

IDENTIFY THE CONJUGATE ACID FOR THE FOLLOWING BASES:

Conjugate Acid

Base

NH4+ NH3

H2CO3 HCO3-

H2S HS-

HBr Br-

IDENTIFY THE ACID, BASE, CONJUGATE ACID, AND CONJUGATE BASE IN THE FOLLOWING CHEMICAL REACTIONS:

1. HCl + OH- Cl- + H2O

acid base c. base c. acid

2. HNO3 + OH- NO3- + H2O

3. H2O + HCO3- H2CO3 + OH-

IDENTIFY THE ACID, BASE, CONJUGATE ACID, AND CONJUGATE BASE IN THE FOLLOWING CHEMICAL REACTIONS:

1. HCl + OH- Cl- + H2O

acid base c. base c. acid

2. HNO3 + OH- NO3- + H2O

acid base c. base c. acid

3. H2O + HCO3- H2CO3 + OH-

acid base c. acid c. base

AMPHOTERIC SUBSTANCES

• An amphoteric substance can donate AND accept protons.

• Example: HCO3- is amphoteric

HCO3- + NH3 CO3

2- + NH4+

Acid Base C. Base C. Acid

HCO3- + H3O+ H2CO3 + H2O

Base Acid C. Acid C. Base

15.2 ACIDITY, BASICITY, AND PH

• Objective:• To calculate the concentration of the hydronium ion and the hydroxide ion.

SELF-IONIZATION OF WATER

H2O(l) + H2O(l) H3O+(aq) + OH-(aq)

[H3O+] = [OH-] = 1.00 x 10-7 M

What is the Keq for water?

SELF-IONIZATION OF WATER

H2O(l) + H2O(l) H3O+(aq) + OH-(aq)

[H3O+] = [OH-] = 1.00 x 10-7 M

What is the Keq for water?

Keq = [H3O+][OH-] = (1.00 x 10-7)(1.00 x 10-7)

Keq = 1.00 x 10-14 = Kw

SUMMARY

Kw = [H3O+][OH-]

Kw = 1.00 x 10-14

DETERMINING [H3O+] AND [OH-] USING KW

• Step 1: Write the Kw expression.

• Step 2: Determine concentrations.• Step 3: Solve!

EXAMPLE

• What is [OH-] in a 3.00 x 10-5 M solution of HCl?

Kw = [H3O+][OH-]

1 x 10-14 = (3.00 x 10-5) [OH-] [OH-] = 3.33 x 10-10 M

PRACTICE

1. Calculate the hydronium ion concentration in an aqueous solution of KOH that has a hydroxide ion concentration of 7.24 x 10-4 M.

PRACTICE

1. Calculate the hydronium ion concentration in an aqueous solution of KOH that has a hydroxide ion concentration of 7.24 x 10-4 M.

2. What is the [OH-] in a 0.450 M solution of HNO3?

PRACTICE

3. What is [H3O+] in a solution of NaOH whose concentration is 3.75 x 10-2 M?

PRACTICE

3. What is [H3O+] in a solution of NaOH whose concentration is 3.75 x 10-2 M?

4. Calculate the hydroxide ion concentration of a 0.200 M solution of HClO4.

15.2: ACIDITY, BASICITY, AND PH CONTINUED

• Objective:• To calculate pH.

PH

• pH: A value used to represent acidity or alkalinity (basicity) of a solution.

MEASURING PH

• Indicators: dyes that turn different colors in solutions of different pH

• Examples: litmus paper, bromothymol blue, methyl orange, phenolphthalein

CALCULATING PH

pH = -log[H3O+]

EXAMPLE

• What is the pH of a solution with a 0.05 M hydronium ion concentration?

pH = -log[H3O+]

pH = -log(0.05)pH = 1.30

*Note: pH does not have units.

PRACTICE

1. What is the pH of 0.00010 M solution of nitric acid?

PRACTICE

1. What is the pH of 0.00010 M solution of nitric acid?

2. Calculate the pH if [H3O+] = 5.0 x 10-3 M.

PRACTICE

1. What is the pH of 0.00010 M solution of nitric acid?

2. Calculate the pH if [H3O+] = 5.0 x 10-3 M.

3. What is the pH of a 0.2 M solution of a strong acid?

15.2: ACIDITY, BASICITY, AND PH

• Objective:• To calculate pOH.

CALCULATING POH

pOH = -log[OH-]

pH + pOH = 14

EXAMPLE

• What is the pH and pOH of 0.00010 M solution of HNO3?

pH = -log[H3O+]pH = -log(0.00010)

pH = 4.0

pH + pOH = 144.0 + pOH = 14

pOH = 10

PRACTICE

1. What is the pH and pOH of a 0.0136 M solution of KOH?

PRACTICE

1. What is the pH and pOH of a 0.0136 M solution of KOH?

2. What is the pH and pOH of a 1.2 x 10-3 HBr solution?

PRACTICE

1. What is the pH and pOH of a 0.0136 M solution of KOH?

2. What is the pH and pOH of a 1.2 x 10-3 HBr solution?

3. What is the pH and pOH of a 2.34 x 10-5 NaOH solution?

15.2: ACIDITY, BASICITY, AND PH

• Objective:

• To calculate [H3O+] and [OH-] from pH.

CALCULATING [H3O+] AND [OH-] FROM PH

pH = -log[H3O+]

[H3O+] = 10-pH

pOH = -log[OH-]

[OH-] = 10-pOH

EXAMPLE

• What are the concentrations of the hydronium and hydroxide ions in a sample of rain that has a pH of 5.05?

[H3O+] = 10-pH

[H3O+] = 10-5.05

[H3O+] = 8.91 x 10-6 M

Kw = [H3O+][OH-] 1 x 10-14 = (8.91 x 10-6)[OH-]

[OH-] = 1.12 x 10-9 M

PRACTICE

1. What is the hydronium ion concentration in a fruit juice that has a pH of 3.3?

PRACTICE

1. What is the hydronium ion concentration in a fruit juice that has a pH of 3.3?

2. A commercial window-cleaning liquid has a pH of 11.7. What is the hydroxide ion concentration?

PRACTICE

1. What is the hydronium ion concentration in a fruit juice that has a pH of 3.3?

2. A commercial window-cleaning liquid has a pH of 11.7. What is the hydroxide ion concentration?

3. If the pH of a solution is 8.1, what is the hydronium ion concentration?

14.3: NEUTRALIZATIONS AND TITRATIONS

• Objective: To determine the concentration of an acid or base used to reach the equivalence point in a titration.

NEUTRALIZATION REACTION(ACID-BASE REACTION)

• General Equation:Acid + Base Salt + Water

• Example:HCl + NaOH NaCl + H2O

TITRATION

• Titration: Method used to determine the concentration of an acid or base.

EQUIVALENCE POINT

• Equivalence Point: Point at which the neutralization reaction is complete

END POINT

• End Point: The instant at which the indicator changes color

TITRATION CALCULATIONS

MAVA = MBVB

where A is acid and B is base

EXAMPLE

• A student titrates 40.0 mL of an HCl solution of unknown concentration with a 0.5500 M NaOH solution. The volume of base solution needed to reach the equivalence point is 24.64 mL. What is the concentration of HCl solution?

Acid (HCl) Base (NaOH)VA = 40.0 mL VB = 24.64 mLMA = ? MB = 0.5500 M

MAVA = MBVB

MA (40.0 mL) = (0.5500 M) (24.64 mL)MA = 0.3388 M

PRACTICE

1. If it takes 25 mL of 0.05 M HCl to neutralize 345 mL of NaOH solution, what is the concentration of the NaOH solution?

PRACTICE

1. If it takes 25 mL of 0.05 M HCl to neutralize 345 mL of NaOH solution, what is the concentration of the NaOH solution?

2. If it takes 50 mL of 0.5 M KOH solution to completely neutralize 125 mL of hydrochloric acid solution, what is the concentration of hyrochloric acid solution?

PRACTICE

3. How much 1.5 M Ca(OH)2 is necessary to exactly neutralize 20.0 mL of 2.5 M sulfuric acid?

PRACTICE

3. How much 1.5 M Ca(OH)2 is necessary to exactly neutralize 20.0 mL of 2.5 M sulfuric acid?

4. A 25.0 mL sample was titrated to the endpoint with 15.0 mL of 2.0 M NaOH. What is the molarity of HCl?

PRACTICE

3. How much 1.5 M Ca(OH)2 is necessary to exactly neutralize 20.0 mL of 2.5 M sulfuric acid?

4. A 25.0 mL sample was titrated to the endpoint with 15.0 mL of 2.0 M NaOH. What is the molarity of Hcl?

5. How much 0.75 M HCl is needed to completely neutralize 25.0 mL of KOH?

15.3: NEUTRALIZATIONS AND TITRATIONS

• Objective: To determine the concentration of polyprotic acids needed to reach the equivalence point in a titration.

TITRATIONS WITH POLYPROTIC ACIDS

MAVA = MBVB

With a twist…

MAVA (#H+) = MBVB(#OH-)

EXAMPLE

• What volume of a 1.366 M solution of NaOH would be required to titrate 47.22 mL of a 2.075 M solution of sulfuric acid?

Acid (H2SO4) Base (NaOH)

MA = 2.075 M MB = 1.366 M

VA = 47.22 mL VB = ? #H+ = 2 #OH- = 1

MAVA (#H+) = MBVB(#OH-)

(2.075 M) (47.22 mL) (2) = (1.366 M) (VB)(1)

VB = 143.5 mL

PRACTICE

1. How much 1.5 M NaOH is necessary to exactly neutralize 20.0 mL of 2.5 M phosphoric acid?

PRACTICE

1. How much 1.5 M NaOH is necessary to exactly neutralize 20.0 mL of 2.5 M phosphoric acid?

2. How much 0.5 M nitric acid is necessary to titrate 25.0 mL of 0.05 calcium hydroxide solution to the endpoint?