Info: The carboxylic groups in a fatty acid can be neutralized by the addition o
ID: 1016285 • Letter: I
Question
Info:
The carboxylic groups in a fatty acid can be neutralized by the addition of potassium hydroxide (KOH). The neutralization reaction is the following:
CH3-(CH2)n-COOH + KOH --> CH3-(CH2)n-COO- K+ + H2O
The mass Index (Ia) is defined as the ratio between MKOH, mass (expressed in mg) of KOH needed to neutralize all the fatty acids, and MFA, the mass of fatty acids (expressed in mg) that was neutralized. Ia = 103 x (MKOH/MFA)
Establish the mathematical equation that links MFA (the mass of fatty acids in your tested sample), MWFA (the molecular weight of the unknown fatty acid) and mFA (the number of moles contained in MFA). Show your reasoning. MFA = ?
Explanation / Answer
CH3(CH2)nCOOH + KOH ------> CH3(CH2)nCOONa + H2O (1)
Fatty acid base soap water
CH3(CH2)nCOOH + OH---------> CH3(CH2)nCOO- + H2O
When KOH solution is added to a solution of the fatty acid, the OH-from the added base and the H+ions from the fatty acid combine to form water. When all the acid has been neutralized at the equivalence-point of the titration
since 1 mole of KOH neutralized for each 1 mole of fatty acid.
it doesn't even account for the 2 atoms of oxygen in each molecule of the fatty acid, let alone the carbon atoms. Somehow a much larger amount of KOH needs to be involved, or a much smaller sample of fatty acid.
The mass Index (Ia) is defined as the ratio between MKOH, mass (expressed in mg) of KOH needed to neutralize all the fatty acids, and MFA, the mass of fatty acids (expressed in mg) that was neutralized. Ia = (MKOH/MFA)
MFA =MKOH
La
MKOH is known Value that is 56 and we know the value of la we can easily calculate the value of MFA
Molecular weight of fatty acid = mass of fatty acid in gram = g/mol
No. of moles of fatty acid
When the formula weight is known, the “n” in CH3 (CH2) nCO2H can be calculated using
n= formula weight – 60.6
14.03
The value 60.6 shows the mass of CH3& COOH group
The value 14.03 shows the mass of CH2
N is unit less quantity.