Post on 02-Apr-2015
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)!!!