post lab discussion: exp. 4

Question 1

saponification

Answer 1

carboxylate salts with very long hydrocarbon chains
made from base hydrolysis of a fat or an oil (made of TG - ester of fatty acids)

Question 2

how are soaps traditionally made

Answer 2

animal fat and lye (NaOH)

Question 3

what happens when esters are treated with NaOH

Answer 3

converted into carboxylate salts which upon neutralization yield carboxylic acids

• the base NaOH breaks the ester bond in the fat

Question 4

what base is usually used in saponification

Answer 4

NaOH or KOH
they are used for hydrolysis
FA are deprotonated (lose H atoms due to the base NaOH or KOH)

a sodium or potassium ion attached
hence they can become charged, they can dissolve in water (more soluble)

Question 5

it has a long nonpolar tail, they are also compatible with nonpolar greases and oils.

Answer 5

carboxylate salts

Question 6

a common soap ingredient

Answer 6

Sodium palmitate
- has 16 C chain
- 1 Na and O atom (water loving)

Question 7

true or false:
saponification under basic conditions is reversible

Answer 7

false - irreversible

Question 8

how are soaps are able to emulsify fats and oils

Answer 8

by forming micelles
- E=enough soap molecules surrounding the oil droplets facilitate the dispersion of the oil droplets in water where they can be easily washed away.

Question 9

what are the methods of breaking down fat or oil molecules

Answer 9

• Using lots of soap:
  could accommodate more fat molecules
• Using hot water:
  can melt solid fats
• Agitation:
  breaks down fats and oils into smaller droplets

Question 10

fats and oils

Answer 10

triesters of glycerol and three fatty acids
- fats, oils and FA r generally insoluble in water bcs of the presence of long hydrophobic tails

Question 11

methodology

Answer 11

Soap preparation (coconut oil + 15ml EtOH + 15ml 20% NaOH + heating & stirring + 50ml 30% NaCl solution)

Vacuum filtration

Comparison to distilled water (negative control) and commercial soap (positive control)

Question 12

negative control vs positive control

Answer 12

Negative Control (Distilled Water):
A negative control shows what happens when there is NO effect
Distilled water has no cleaning/soap properties
It serves as a baseline to show what “no soap activity” looks like
If your experiment works, your soap should perform better than plain water

Positive Control (Commercial Soap):
A positive control shows what a KNOWN working example looks like
Commercial soap is a proven, working soap
It shows what successful soap activity should look like
It lets you compare how well your homemade soap works compared to a known good soap

This helps you determine if your soap preparation was successful by comparing it to both:

Should work better than distilled water (negative)
Should work similarly to commercial soap (positive)

Question 13

formation of negative pressure at the outlet of the filtrate and using it as the driving force of filtration

Answer 13

vacuum filtration

Question 14

what is the use of the vacuum filtration

Answer 14

to obtain a filter residue with low moisture content

Question 15

what is the expected result after the soap soln is subjected to vacuum filtration

Answer 15

formation of white solid clumps with little to no moisture

however,
Some soap samples hardened or formed solid clumps as soon as 50ml of 30% NaCl solution was added, but some soap samples remained liquid even after the ice bath.

Question 16

what are the possible source of errors during the experiment

Answer 16

too much coconut oil was added
a portion of the NaOH soln was not dispensed properly (not adding the right amt)
inadequate mixing

Question 17

how long is the curinng time for soaps

Answer 17

for around 4 weeks where the soap lose more water and become milder
(some become physically harder and longer lasting)

Question 18

what is the expected pH level

Answer 18

that ranges from pH 7 to 10
- soaps that have a pH level greater than 10 are considered lye-heavy
- can irritate or burn the skin

factors to consider:
Saponification reaction takes around 24 hours and continues to become milder with time.

Question 19

what is expected when shaking the soap mixed with water

Answer 19

that the soap becomes colloidal (these particles float around evenly) in nature
agitating

Question 20

comparison of the foaming capacity of the soap samples is usually based on

Answer 20

the height of the foam created after agitation

Taller foam = stronger soap action
Shorter foam = weaker soap action

Question 21

substances that reduce the surface tension in the liquid

Answer 21

surfactant

Soap reduces the surface tension of the water, making the water molecules less likely to stick together and more likely to interact with oil or grease.

Question 22

soap interaction with oil

Answer 22

hydrophilic part:
interact with the water molecules in solution, forming the outer surface of the micelle

hydrophobic part:
interacts with the oil, trapping the oil in the center

[As the soapy water is rinsed away, the oil/grease goes along
with it.]

Question 23

hard water test

Answer 23

hard water:
water that contains a significant concentration of Mg2+ and Ca2+ ions.
these ions form precipitates with soap molecules which is often characterized as a gray line on a bathtub or sink called “soap scum”

soft water:
water that contains very few or no ions that precipitate with soap
more soap molecules are available in solution that can interact with oil molecules, making soaps much more effective in soft water than
in hard water

[soaps are less effective in hard water]

Question 24

what happens as the soap molecules form precipitates with these ions, most of the soap molecules are no longer present in solution.

Answer 24

less emulsification capacity lass foam formed

Question 25

how are detergents are similar to the soap

Answer 25

that they also have a charged head group
a long hydrophobic tail

Question 26

what are the advantages of using detergents

Answer 26

work effectively both in soft and hard water as they do not form precipitates with Mg2+ and Ca2+

Question 27

a typical ingredient found in commercial shampoos and other cleaning products

Answer 27

sodium lauryl sulfate.
(structure)

Question 28

why is detergents not able to be broken down in sewage treatment plants

Answer 28

due to sodium lauryl sulfate being a nonbiodegradable detergent

Question 29

biodegradable detergents were developed substituting sodium lauryl sulfate with other biodegradable compounds like

Answer 29

sodium laurylbenzenesulfonate

Question 30

why are some commercial detergents are also being advertised as being “phosphate-free”

Answer 30

advantageous for the environment as excessive amounts of phosphate in bodies of water accelerates the growth of algae which consumes too much of the dissolved O2 in water.

ecosystem in these bodies of water are disturbed, also negatively affecting the species that inhabit these ecosystems.

Question 31

what facilitates the lipid emulsification in the body

Answer 31

primarily facilitated by bile salts

amphipathic nature of bile salts aid in the digestion of fat droplets in the body, preventing their reaggregation

Question 32

where is the bile stored

Answer 32

gallbladder

stimulated to contract and secrete the bile when food passes from the stomach into the duodenum

Question 33

why is bile salts are steroidal detergents

Answer 33

form mixed micelles with lipids, fats, and/or cholesterol, and thus enable the digestion and absorption of fats and fat-soluble vitamins in the intestine

Question 34

this removes the aur and creates a vacuum to vacuum the water out

Answer 34

buchner flask