Saponification number.ppt

Chemistry

1. Determination of
Saponification Number

2. Determination of Saponification Number
Onrefluxingwithalkali,triacylglycerols(fatty
acidesters)arehydrolyzedtogiveglycerol
andpotassiumsaltsoffattyacids(soap).
Suchprocessisknownas,Saponification.

3. Determination of Saponification Number
H2O
Δ

4. Determination of Saponification Number
•Thesaponificationvalue
isthenumberofmilligramsofKOHrequiredto
neutralizethefattyacidsresultingfromthe
completehydrolysisof1goffat.

5. Determination of Saponification Number
■Thesaponificationvaluegivesan
indicationofthenatureofthefatty
acidsconstituentoffatandthus,
dependsontheaveragemolecular
weightofthefattyacidsconstituent
offat.
•Thegreaterthemolecularweight(the
longerthecarbonchain),thesmaller
thenumberoffattyacidsisliberated
pergramoffathydrolyzedand
therefore,thesmallerthe
saponificationnumberandviceversa.

6. Materials:
1-Fats and oils (olive oil, coconut oil, sesame oil, and
butter)
2-Fat solvent (equal volumes of 95% ethanol and ether)
3-Alcholic KOH (0.5 mol/liter)
4-Reflux condenser.
5-Boiling water bath.
6-Phenolphethalein.
7-Hydrochloric acid (0.5 mol/liter)
8-Burettes (10 ml and 25 ml)
9-Conical flasks (250ml)

7. 1 ml fat
3 ml fat solvent
25 ml alcoholic KOH
Heat flask on a boiling water bath for 30 min.
Leave to cool to room temperature
0.5mol/L
HCL
Phenolphthalein
(Ph.ph)

8. Calculations:
•Thedifferencebetweentheblankandthetest
readinggivesthenumberofmillilitersofKOH
requiredtosaponify1gfat.
•Youcanusethisformulatocalculatethe
saponificationvalue:
1ml(0.5NHCl)=28.05mgKOH
(B-T)=S
■Saponificationvalue(S)=
(B-T)x28.05= mgKOH/1g
Wt.offat(1g)