Conjugate acids and bases
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Conjugate acids and bases

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Conjugate acids and bases




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Presentation on theme: "Conjugate acids and bases"— Presentation transcript:

Slide1

Conjugate acids and bases

Slide2

Different definitions of acids and bases

Acids are proton donors (

Brønsted

Lowry definition)

they generate H

3

O

+

in water (Arrhenius definition)

Bases are proton acceptors

they generate OH

-

in water

which is an acid/base?

HF +

H

2

O

H

3

O

+

+ F

-

NaHCO

3

+

H

2

O

Na

+

+H

2

O + CO

2

+ OH

-

Slide3

Follow the proton

HF + H2O  H3O+ + F-NaHCO3 + H2O  Na++ H2O+CO2 +OH-Joining equilibrium to acid base…What about the reverse reaction?

H

+

H+

H

+

H

+

Slide4

Conjugate acids and bases

When you run the reverse reaction you find the products are also acids and bases. The acids and bases that are formed are called

conjugate acids or bases

H

2

O

+

HF

H

3

O

+

+

F

-

base

acid

conjugate acid

conjugate base

NaHCO

3

+

H

2

O

Na

+

+H

2

O + CO

2

+

OH

-

base

acid

CA

CB

Slide5

Label Acid, Base, Conjugate Acid, Conjugate Base

HClO

3

+

H

2

O

ClO

3

-

+

H

3

O

+

A B CB CA

ClO

-

+

H

2

O

HClO

+

OH

-

B A CA CB

HSO

4

-

+ H

2

O

SO

4

2-

+

H

3

O

+

A B CB CA

LiOH

+ H

2

O

Li

+

+ H

2

O

+

OH

-

B A CA CB

Slide6

Conjugate acids and bases …

Conjugate acids and bases determine if an acid or base is strong or weak.

If the conjugate acid/base readily reacts to run the reverse reaction it is a

weak

acid/base.

If it does

not

react in the reverse reaction the acid or base is

strong.

Slide7

Strong acids

Acid

formula

Nitric Acid

HNO

3

Sulfuric Acid

H

2

SO

4

Hydrochloric acid

HCl

Slide8

Strong Bases

NameFormulaNameFormulaSodium HydroxideNaOHCalcium HydroxideCa(OH)2Potassium HydroxideKOHStrontium HydroxideSr(OH)2Barium HydroxideBa(OH)2

these make a lightning bolt

on the periodic table!

Slide9

More with conjugate acids/bases

H

2

SO

4

+ H

2

O

H

3

O

+

+ HSO

4

-

Sulfuric acid is a

strong

acid so its conjugate

base

, HSO

4

-

, will

not

run the reverse reaction.

HSO

4

-

is actually an acid in water.

HSO

4

-

+ H

2

O

H

3

O

+

+ SO

4

2-

SO

4

2-

will run the reverse reaction, so it is a

weak

acid

Slide10

Other weak acids and bases

Weak Acids

Acetic Acid (vinegar)

Citric Acid

Ascorbic Acid (vitamin C)

Boric Acid

Carbonic Acid

Weak Bases

Sodium Bicarbonate

Ammonia

Sodium Hypochlorite (bleach)

Slide11

Danger!!!

Strong and Weak acids and bases do NOT necessarily tell you how dangerous they are.

Concentration is the most important factor for determining danger.

Ammonia is a weak base, if it is highly concentrated it can burn you.

Dilute hydrochloric acid (less than 1 M) is not particularly dangerous

Slide12

What is water

Water is either an acid or base depending on the situation.

Anything that is either an acid or a base is called

amphoteric

.

Several things are amphoteric, like parts of you.

Slide13

Donating Protons

Hydrochloric acid (HCl) can donate 1 proton, so it is called a

monoprotic acid

.

Sulfuric acid (H

2

SO

4

) can donate 2 protons, so it is called a

diprotic acid

.

Phosphoric acid (H

3

PO

4

) can donate 3 protons, so it is called a

triprotic acid

.