Topics for Today

From Fats to Soap!

Topics for Today

What is a soap? Why do soaps clean? What is dirt? What is hard water? How do we make a soap?

Readings for Today

Section 5.12.1 – How Hard is Your Water?

Topics for Wednesday

From Soap to Biodiesel!!

Topics for Wednesday

Why biodiesel? How are soap and biodiesel different?

No text readings

Topics for Friday

EXAM 4!!!!

Announcements!

HW 5 due Thursday the

10th!

Final Exam!!

Friday, May 18th

Final Exam!!

Can I take it early?

Chancellor John Wiley

Only if you have 3 finals

within 24 hours of each

other

Topics for Today

From Fats to Soap!

Generic term for the soluble salt of a fatty acid

What is a soap?

Generic term for the soluble salt of a fatty acid

What is a soap?

Review

What is a salt?

The product of an acid-base

reaction!

Neutralization Reaction

HNO3 + NaOH

H+ NO3- Na+ OH

- Na+ NO3- H+ OH

-

Acid + Base Salt + Water

NaNO3 + HOH

There WILL be a neutralization reaction (in some fashion) on

Exam #4!!

Can you use carboxylic

acids?

Carboxylic Acids

C

OH

O

CH3

Ethanoic/Acetic Acid (Vinegar)

CH3COO- (Acetate ion) H+

Where does the H+ come

from?

Neutralization Reaction- Review

C

OH

O

CH3 + NaOH H2O+CO- Na+

O

CH3

Acid + Base Salt + Water

Acetic Acid + NaOH Sodium Acetate + H2O

Soap

Generic term for the soluble salt of a fatty acid

Review

What is a fatty acid?

Fatty Acids + Alcohol Triglyceride + Water H+Three Triple

Fats Oils

Another triglyceride…

H | H—C—O—C—(CH2)16CH3 | H—C—O—C—(CH2)7CH=CH(CH2)7CH3

| H—C—O—C—(CH2)14CH3

| H

=

O

=O

+ 3 HOH

=

O

from stearic acid

from

palmitic acid

from oleic acid

Neutralization Reaction

C

OH

O

CH3 + NaOH H2O+CO- Na+

O

CH3

Acid + Base Salt + Water

Acetic Acid + NaOH Sodium Acetate + H2O

Try another one!!

Stearic Acid

CH3(CH2)16COOH

CH3(CH2)16CO

OH

C

OH

O

CH3 +NaOH

H2O+Na+

(CH2)16

C

O-

O

CH3 (CH2)16

Acid + Base

Salt + Water

Review

C

OH

O

CH3 +NaOH

H2O+Na+

(CH2)16

C

O-

O

CH3 (CH2)16

Fatty Acid + Base

Soap + Water

Review

Soap

Generic term for the soluble salt of a fatty acid

Salt of a Fatty Acid (Soap!!)

CH3(CH2)16 C

O

O- Na+

Salt of a Fatty Acid (Soap!!)

CH3(CH2)16 C

O

O- Na+

How does a soap work?

Salt of a Fatty Acid (Soap!!)

CH3(CH2)16 C

O

O- Na+

Polar or nonpolar?

Salt of a Fatty Acid (Soap!!)

CH3(CH2)16 C

O

O- Na+

Polar or nonpolar?

Salt of a Fatty Acid (Soap!!)

CH3(CH2)16 C

O

O- Na+

Polar or nonpolar?

Salt of a Fatty Acid (Soap!!)

CH3(CH2)16 C

O

O- Na+

Polar or nonpolar?

NONPOLAR CHAIN

POLAR (IONIC) END

Salt of a Fatty Acid (Soap!!)

CH3(CH2)16 C

O

O- Na+

A molecule with dual

personalities!

NONPOLAR CHAIN POLAR (IONIC) END

Different parts of the molecule

behave differently!

REVIEW - TYPES OF BONDSREVIEW - TYPES OF BONDS

Electronegativity Difference

Low High

IONICPOLARNONPOLAR

COVALENT

Salt of a Fatty Acid (Soap!!)

Squiggly Notation

NONPOLAR CHAIN

POLAR (IONIC) HEAD

+

What about grease? What are its

properties?

What is grease?

A bunch of fats and

oils!!

Polar or nonpolar?

Another triglyceride…

H | H—C—O—C—(CH2)16CH3 | H—C—O—C—(CH2)7CH=CH(CH2)7CH3

| H—C—O—C—(CH2)14CH3

| H

=

O

=O

+ 3 HOH

=

O

from stearic acid

from

palmitic acid

from oleic acid

From Crude Oil

Polar or nonpolar?

Dirt and Grease

A bunch of nonpolar

molecules

How does soap clean?

1) The soap traps the grease

GREASE

Polar Head

Nonpolar Tail

water

water

water water

water

waterwater

Figure 5.21

(p. 249)

2) The water washes away the

soap + grease

OHH

.. ..

Polar Head

Polar Molecule

Why?

1) The soap traps the grease

GREASE

Polar Head

Nonpolar Tail

water

water

water water

water

waterwater

How do we make a soap?

C

OH

O

CH3 +NaOH

H2O+Na+

(CH2)16

C

O-

O

CH3 (CH2)16

Neutralize a fatty acid?

We don’t just have fatty acids sitting

around in our world…

Where can we get them?

Fats!

We need to hydrolyze a

fat!!

Step 1) Hydrolysis

A chemical reaction where you ADD water!!

Polyester Nylon

Opposite of condensation

reactions!!

Review - Condensation

Carboxylic Acid + Alcohol Ester + Water H+

Hydrolysis!

Ester + Water Alcohol + Carboxylic Acid OH-

Break the ester into its “original”

parts!

Where can we find an ester?

Fats!

Hydrolysis!

Ester + Water Alcohol + Carboxylic Acid OH-

Break the ester into its “original”

parts!

Hydrolysis!

Ester + Water Alcohol + Carboxylic Acids OH-

Break the ester into its “original”

parts!

Triple Triple Three

OR…

Hydrolysis!

Fat + Water Glycerol + Fatty Acids OH-

Break the ester into its “original”

parts!

Three

Example

Glycerol Tristearate

C OH

C O

OCH

H

H

H

C(CH2)16CH3

O

C(CH2)16CH3

O

C(CH2)16CH3

O

TRIPLE ESTER!

Hydrolyze…

C OH

C O

OCH

H

H

H

C(CH2)16CH3

O

C(CH2)16CH3

O

C(CH2)16CH3

O+ 3 H2O

NaOH

C OH

C O

OCH

H

H

H

H

H

H

+ O C(CH2)16CH3

OH3

Name? Glycerol!!

FATTY ACID!

Heat

O C(CH2)16CH3

OH3

This isn’t soap! Now what?

Soap

Generic term for the soluble salt of a fatty acid

Neutralize the fatty acid!

C

OH

O

CH3 +NaOH

H2O+Na+

(CH2)16

C

O-

O

CH3 (CH2)16

Fatty Acid + Base

Soap + Water

Review

Sopanification

The process of making soap 1) Hydrolysis of the fat 2) Neutralizing the fatty acid

Sopanification

The process of making soap

Heating a triglyceride (usually a fat) in the presence of a base

Sopanification

HEAT / H2OC OH

C O

OCH

H

H

H

CO

CO

CO

3NaOH+

CH O

CH2 O

OCH2

H

H

H

+ C

O-

O

CH3 (CH2)163

Na+

Why is water not in the reaction?

Sopanification

The process of making soap 1) Hydrolysis of the fat (water is used) 2) Neutralizing the fatty acid (water is

produced)

It’s a wash!!!

When soaps DON’T work…

What is hard water?

Water with lots of Ca2+

and Mg2+ ions

How do these ions get into the

water?

Review

Dissolving a salt…

2HCl+ Na2CO3 H2CO3 2NaCl+

Why the “2”?

Review Dissolving a salt…

2HNO3 + CaCO3 Ca(NO3)2 + H2CO3

H2CO3 H2O + CO2

A lot of limestone in our area… tend to

have very hard water

What does this have to do with

soaps?

Soluble in water

“Separates” into ions

Soap in “normal” water

Soap in “normal” water

C

O -

O

Na+

CO-

O

CO

-

O

CO-

O

Na+

Na+

Na+

Soap interacts with the Mg2+ and Ca2+ ions.

Soap in hard water

NOT soluble!!!!

Soap in hard water

Mg2+

CO-

O

CO-

O

Mg2+

CO-

O

CO-

O

Na+

Na+Na+

Na+

Soap forms complexes

with Mg2+ and Ca2+!!

So what?

Soap in hard water

Mg2+

CO-

O

CO-

O

Mg2+

CO-

O

CO-

O

Na+

Na+Na+

Na+

Insoluble in water (soap scum)!!!