Fats and Oils: Uses of Esters
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Draw the structure of 4-ethyloct-3-ene
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Draw the structure of propane-1,2,3-triol
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What is an emulsion? (mxtr. 2 lqds. dnt. dslv. in 1anthr.)
A mixture of two liquids that do not dissolve in one another
What is the difference between a fat and an oil? (fts. sld. RT. -ols. lqd. RT)
Fats are solid at room temperature, while oils are liquid at room temperature
Why are fats and oils called triglycerides? (trsts. frmd. frm. glycrl. + 3 fty. acd. mlcls. )
Because they are triesters formed from glycerol and three fatty acid molecules
What are the products when fats and oils are hydrolysed under acidic conditions? (glcycl. + 3x fty. acds)
A mixture of glycerol and three fatty acids
What are the products when fats and oils are hydrolysed by boiling with sodium hydroxide (NaOH) or potassium hydroxide (KOH)? (glcycl. + slts.)
Glycerol and sodium (or potassium) salts of the fatty acids (which are soaps)
Why are saturated fatty acids considered less healthy? (blck. bld. vsls. + ld. hrt. dses. )
They can block blood vessels and lead to heart disease
Two possible arrangements of atoms around a double bond in an unsaturated fatty acid?
Cis and Trans configurations
How does the cis configuration affect the shape of a fatty acid chain? (intr. knk. chn. prvntg. cls. pckng. mlcls.)
It introduces a kink in the chain, preventing close packing of molecules
Why are cis - unsaturated fatty acids (oils) usually liquids at room temperature? (knks. rdc. int. forces btwn. chns. mkng. unbl. pck. clsly. rsltng. wkr. atrctns. + lwr. mp. frmng. oils.)
The kinks reduce the intermolecular forces between the chains, making them unable to pack closely, resulting in weaker attractions and a lower melting point (forming oils)
What are trans - unsaturated fatty acids like at room temperature? (lnr. pck. clsly. + sld.)
They are more linear, can pack closely, and tend to be solid like fats
What are three main properties of triglycerides? • lng. trm. engry. strge. • lng. non plr. crbn. chns. = inslbl. wtr. • slble. non plr. slvnts. - E
• They act as long - term energy storage in the body • Their long non - polar carbon chains make them insoluble in water • They are soluble in non - polar solvents such as esters
What are the conditions needed for the acid hydrolysis of fats and oils?
The fat/oil is heated with acidic water (under acidic conditions)
How are soaps made from glycerol - containing esters? (alk. hydro. - spnfctn. estrs. prdcng. glycrl. + Na slts. fty. acds.)
By alkaline hydrolysis (saponification) of esters, producing glycerol and sodium salts of fatty acids (soaps)
Outline this chemical reaction between fat and sodium hydroxide
Form salt + glycerol
What are the two distinct parts of the RCOO- ion (soap molecule)?
The hydrophobic hydrocarbon chain that mixes with grease and the hydrophilic COO- group that mixes with water
How do soap molecules help remove grease? (non plr. tl. dslvs. grse. + plr. hd. intrcts. w/ wtr. alwng. grse. + tr. mx. frmng. emlsn/ - wshd. awy.)
The non - polar tail dissolves in grease, and the polar head interacts with water, allowing grease and water to mix, forming an emulsion that can be washed away
Why is glycerol very soluble in water?
It contains three -OH (hydroxyl) groups, allowing it to form multiple hydrogen bonds with water molecules
What type of intermolecular forces does glycerol form?
Hydrogen bonds