Determination Of An Unknown Amino Acid From Titration Essay -- essays

Determination of An Unknown Amino Acid From TitrationAbstractExperiment 11 used a titration curve to determine the identity of an incomprehensible aminic acid. The initial pH of the solution was 1.96, and the pKas give experimentally were 2.0, 4.0, and 9.85. The current pKa set werefound to be 2.10, 4.07, and 9.47. The molecular angle was calculated to be176.3 while the accepted value was found to be 183.5. The identity of theunknown aminic acid was established to be glutamic acid, hydrochloride.IntroductionAmino acids atomic number 18 simple monomers which atomic number 18 strung together to form polymers(also called proteins). These monomers are characterized by the general organise shown in figure 1.Fig. 1Although the general structure of all amino group acids follows figure 1, the presenceof a zwitterion is made assertable due to the raw material properties of the NH2 groupand the acidic properties of the COOH group. The amine group (NH2) is Lewis humble because it has a lone electron pair which makes it susceptible to a line up covalent bond with a hydrogen ion. Also, the carboxylic group is aLewis acidic because it is able to donate a hydrogen ion (Kotz et al., 1996).Other forms of amino acids also exist. Amino acids may exists as acidic orbasic salts. For lawsuit, if the glycine reacted with HCl, the resulting aminoacid would be glycine hydrochloride (see fig. 2). Glycine hydrochloride is anexample of an acidic salt form of the amino acid. Likewise, if NaOH were added,the resulting amino acid would be sodium glycinate (see fig. 3), an example of abasic salt form.Fig. 2Fig. 3Due to the nature of amino acids, a titration curve can be employed to identifyan unknown amino acid. A titration curve is the temporary hookup of the pH versus the potof titrant used. In the case of amino acids, the titrant will be both an acidand a junior-grade. The acid is a useful beam because it is able to add a proton to theamine group (see fig. 1). Likewise the base allows for removal of the protonfrom the carboxyl group by the addition of hydroxide. The addition of the tight acid or base does not necessarily yield a drastic jump in pH. The acidor base added is unable(p) to contribute to the pH of the solution because theprotons and hydroxide ions donated in solution are busy adding protons to theamine gr... ...unded series of crude estimates which wererequired. Likewise, the deviance of the calculated molecular weight can beattributed to these crude vehicles, because the change in garishness (betweenequivalence points) were used in calculation.ConclusionThe identity of an unknown amino acid was determined by establishing atitration curve. The equivalence and half-equivalence point, the pKa values,and the molecular weight were directly or indirectly found through the titrationcurve. The equivalence points were found through a crude method known as thetrapezoidal method. The establishment of the equivalence points gave rise tothe half eq uivalence points and the D volume (used in calculating the molecularweight). The half-equivalence points were directly used to find the pKa valuesof the unknown. The molecular weight could also be calculated. This data led tothe tendency of the identity of the unknown amino acid--glutamic acid,hydrochloride.ReferencesJicha, D. Hasset, K. Experiments in General Chemistry hunting Dubuque, 199137-53.Kotz, J.C. Treichel , P. Jr. Chemistry and Chemical Reactivity Harcourt-BraceFort Worth, 1996 816-837.