Chemistry and Biochemistry Academy

Question A chemist determined the levels of iron in dry leaves collected from a plant near her homestead, she weighed 15 grams of the leaves and dissolved them in a mixture of acids, filtered the resulting solution in a 250mlvolumeric flask. She pipetted 10mls of the solution to a 50ml volumetric flask and topped it to the mark using deionized water. This solution gave absorbance of 0.56. She pipetted another 10mls into another 50ml flask, added 4mls of 3 x 10^ -4 M iron solution and made it to the mark with deionized water. This solution gave absorbance of 0.72. (i)                   Calculate the concentration of iron in prepared leaf solution? (ii)                 Calculate the concentration of iron in the leaves in mg/g of the leaves? This question needs the application of the formula of “standard addition method’’. The formula is given by: SSVf/ ((Cx Vx) + (CsVs)) = SVf/ (CxVx) ; Where: SS - represent absorbance of the spiked sample S -Represent absorbance

Can glycerol and lye make soap? The answer is no. This is due to glycerin is a by-product of soap making process.   The process (saponification/hydrolysis) takes place as follows: hydroxyl group ( - OH)-nucleophile of the base (lye) which can   either be sodium hydroxide (NaOH) or potassium hydroxide (KOH) attacks the carbonyl of TAG(triglyceride) thus cleaving the ester bonds between the glycerol carbon number 1-3 and long-chain of carboxylic acid. This lead to formation of alkoxide and carboxylic acid (let R, R 1 represent long hydrocarbon chain of the acid and alkoxide respectively, that isRCO 2 H and R(O - ) 3 )but since the alkoxide is stronger base than the hydroxyl group of carboxylic acid this enhance proton (H + ) transfercarboxylicacid to alkoxide. This results in formation glycerol (R 1 (OH) 3 )and carboxylate ion (RCO 2 - ) which then attacks cation (Na + or K + ) hence yielding soap. Glycerol is just an additive in soap if it isnot removed, but in commercialmanufac