i. introduction to acids & bases ch. 19 – acids & bases

I. Introduction toAcids & Bases

I. Introduction toAcids & Bases

Ch. 19 – Acids & BasesCh. 19 – Acids & Bases

A. PropertiesA. Properties

electrolytes electrolytes

turn litmus red

sour taste

react with metals to form H2 gas

slippery feel

turn litmus blue

bitter taste

vinegar, milk, soda, apples, citrus fruits

ammonia, lye, antacid, baking soda

B. DefinitionsB. Definitions

ArrheniusArrhenius

HCl + H2O H3O+ + Cl–

•Acids Acids contain hydrogencontain hydrogen

•AcidsAcids form hydronium ions (H3O+) in aqueous solution

H

HH H H

H

ClClO O

–+

acid


ArrheniusArrhenius•Bases Bases contain a hydroxide groupcontain a hydroxide group•BasesBases form hydroxide ions (OH-) in

aqueous solution

NaOH Na+ + OH-

base

H2O


Brønsted-LowryBrønsted-Lowry

HCl + H2O Cl– + H3O+

•AcidsAcids are proton (H+) donors

•BasesBases are proton (H+) acceptors

conjugate acidconjugate base

baseacid


Brønsted-LowryBrønsted-Lowry

HBr + NaOH NaBr + H2O

•Conjugate AcidsConjugate Acids are the result after a base accepts a hydrogen ion

•Conjugate BasesConjugate Bases are the result after an acid donates a hydrogen ion

conjugate acidconjugate base

baseacid


H2O + HNO3 H3O+ + NO3–

CBCAAB

H2O + NH3 NH4+ + OH-

CA CBBA

Amphoteric – can be an acid or a base – can be an acid or a base


F -

H2PO4-

H2O

HF

H3PO4

H3O+

Give the conjugate base for each of the following:

Polyprotic – an acid with more than one H – an acid with more than one H++


Br -

HSO4-

CO32-

HBr

H2SO4

HCO3-

Give the conjugate acid for each of the following:

C. StrengthC. Strength

Strong Acid/BaseStrong Acid/Base• 100% ionized in water• strong electrolyte

- +

HCl

HNO3

H2SO4

HBr

HI

HClO4

NaOH

KOH

KOH

RbOH

CsOH

Ca(OH)2

Ba(OH)2

C. StrengthC. Strength

Weak Acid/BaseWeak Acid/Base• does not ionize completely• weak electrolyte

- +

HF

CH3COOH

H3PO4

H2CO3

HCN

NH3

Ch. 19 – Acids & BasesCh. 19 – Acids & Bases

II. pH

(p. 644 – 658)

II. pH

(p. 644 – 658)

pH water equilibriumpH water equilibrium

Pure water ionizes to a small extent to produce hydrogen ions and hydroxide ions

According to LeChatlier’s principle if an acid is dissolved in water the equilibrium will shift to the left decreasing the hydroxide ion concentration.

If a base is dissolved in water this decreases the hydrogen ion concentration.

A. Ionization of WaterA. Ionization of Water

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

(aq)

Self-Ionization of Water

Ion Product Constant for Water

• For all aqueous solutions, the product of the hydrogen-ion concentration and the hydroxide-ion concentration equals 1.0 x 10-14

• The ion production of water, Kw = [H3O+][OH–]

• Pure water contains equal concentrations of H+ and OH– ions, so [H3O+] = [OH–]


Kw = [H3O+][OH-] = 1.0 10-14


Find the hydroxide ion concentration of 3.0 10-2 M HCl.

[H3O+][OH-] = 1.0 10-14

[3.0 10-2][OH-] = 1.0 10-14

[OH-] = 3.3 10-13 M

HCl → H+ + Cl-

3.0 10-2M 3.0 10-2M


Find the hydronium ion concentration of 1.4 10-3 M Ca(OH)2.

[H3O+][OH-] = 1.0 10-14

[H3O+][2.8 10-3] = 1.0 10-14

[H3O+] = 3.6 10-12 M

Ca(OH)2 → Ca2+ + 2 OH-

1.4 10-3M 2.8 10-

3M

pH = -log[H3O+]

B. pH ScaleB. pH Scale

0

7INCREASING

ACIDITY NEUTRALINCREASING

BASICITY

14

pouvoir hydrogène (Fr.)“hydrogen power”


pH of Common SubstancespH of Common SubstancespH of Common SubstancespH of Common Substances


pH = -log[H3O+]

pOH = -log[OH-]

pH + pOH = 14


What is the pH of 0.050 M HNO3?

pH = -log[H3O+]

pH = -log[0.050]

pH = 1.30

Acidic or basic?Acidic


What is the pH of 0.050 M Ba(OH)2?

[OH-] = 0.100 M

pOH = -log[OH-]

pOH = -log[0.100]

pOH = 1.00

pH = 13.00

Acidic or basic? Basic


What is the molarity of HBr in a solution that has a pOH of 9.60?

pH + pOH = 14

pH + 9.60 = 14

pH = 4.40

Acidic

pH = -log[H3O+]

4.40 = -log[H3O+]

-4.40 = log[H3O+]

[H3O+] = 4.0 10-5 M HBr

i. introduction to acids & bases ch. 19 – acids & bases

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h slide

h triprotic

h triprotic

h diprotic

h diprotic

h polyprotic

cooh h

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