Fats, oils, soaps, and biodiesel wace

Question 1

Describe fats and oils

Answer 1

-lipids
-come from plants and animals
-animal fats usually solid at room temp and saturated
-oil normally liquid and unsaturated

Question 2

Describe the structure of fats and oils
Add examples of reaction which forms triglycerides

Answer 2

-contain large, non-polar molecules (triglycerides)
-insoluble in water
-synthesised by condensation reaction between glycerol (OH) and 3x fatty acids (COOH)
-ester functional group formed + 3H2O

Question 3

Describe the difference between saturated and unsaturated fatty acids

Answer 3

saturated: all C-C bonds are single e.g. stearic acid in meats
monounsaturated: contain one C-C double bond e.g. oleic acid in vegetable oils
polyunsaturated: more than one C-C double bond e.g. linoleic acid in fish and vegetable oil

Question 4

What is the use of fats and oils

Answer 4

-75% productions of food, directly as ingredient, to fry, or as fuel for cooking
-25% used as raw material e.g. inks, candles, paints, soap

Question 5

What is soap
What is it made up of

Answer 5

-act as emulsifiers
-contain a long non-polar hydrocarbon chain
-polar carboxylate ion at head
-metal ion (normally Na or K)
-manufactured by breaking ester bond in triglyceride (saponification)

Question 6

Describe saponification
Provide the example equation (triglyceride plus base)

Answer 6

-breaking ester bond of triglyceride requires water (hydrolysis) and a strong base (NaOH or KOH) to speed up hydrolysis-base hydrolysis
-fatty acid anion and metal cation from base used in hydrolysis are the soap

Question 7

Contrast soft water and hard water with soap

Answer 7

-soft water forms lather with soap
-hard water needs more soap to form a lather, adding additional cost to cleaning process

Question 8

Describe hard water

Answer 8

contains high concentration of calcium and magnesium ions

Question 9

Describe the reaction of soap with oils/fatty acids in soft water

Answer 9

-fatty acid and sodium dissociate to form sodium ions and fatty acid ions
-fatty acid ions have non-polar end and polar head
-non-polar end is attracted to the oil (hydrophobic) and head is attracted to the water (hydrophilic), -if enough soap molecules have attached to oil, w/ agitation, soap molecules will pull oil from fabric.

Question 11

Describe the reaction of soap with oils/fatty acids in hard water
Compare the reaction of detergent with hard water?

Answer 11

-hard water is water containing a high concentration of Mg2+ and Ca2+
-the soap ions will react with these ions to form an insoluble compound called scum.
-soap will only form lather if all calcium ions precipitated out
-Detergent ions react with the Ca and Mg ions to form a soluble compound therefore does not require more detergent to form a lather
-Both soaps and detergents form micelles in water

Question 12

What are the negative effects of soap in hard water

Answer 12

-more soap needed to lather=poorly washed clothes and increase cost
-difficult to clean scum from bathtubs and sinks as insoluble
-scum blocks drains
-hard water=unsuitable for industrial process like dying clothes

Question 13

Describe detergents
Revise over equation to make detergents

Answer 13

Soapless cleaning agent made form crude oil, rather than vegetable oil/animal fats
-made of long hydrophobic carbon chains
-hydrophilic end is sulfonate

Question 14

Compare and contrast soap with detergents

Answer 14

soap:
-form scum w/hardwater
-biodegradable

detergents
-no scum as form soluble compounds
-can be made from by-products of oil refining process (cheaper)
-non-biodegradable stay in water=froth

Question 15

Describe the cleaning action of soap

Answer 15

-polar molecule able to form H bond with water
-with agitation, micelle dump will break up
-non-polar end of molecule will position self in drops of oil/grease
-polar head attracted to water
-once enough soap molecule attached to oil, polar heads attracted to water will lift oil particles form fabric, with agitation
-surfactant (surface active agent)

Question 16

Describe the production of biodiesel/transesterification
Provide example of equation

Answer 16

-alternative to non-renewable fossil duels
-raw materials utilised are commonly soyabeans, canola or palm oil
-triglycerides convert to biodiesel by warming with alcohol (transesterification)
-reaction requires catalyst either bas-catalyst (KOH or NaOH) or a lipase(enzyme)-catalyst

Question 17

Compare base-catalyst and lipase-catalyst

Answer 17

-biodiesel production uses base-cat most of the time
-allows manufacture w/methanol and occurs at high temperatures (quicker)

-lipase is preferred can be repeated
-requires less energy and at low temp/pressures (cost efficient)
-however, slower process (lower yield