Carboxylic Acid Lab Report

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As shown in the data above, 34 different organic acids were used to investigate the effect certain factors possibly have on solubility. To ensure that the conclusions drawn were as accurate as possible, different structural factors were taken into account when looking at the carboxylic acids and amino acids. Table 1 presents the molar mass in g/mol−1, number of carboxylic acid groups, number of amino groups, and solubility in water in g/L of each. As well as having the numerical value of the solubilities, each was also translated as being either completely\almost completely miscible, soluble, poorly soluble, or completely\almost completely insoluble. The section filled in yellow indicates that the data pertains to samples of carboxylic acids,…show more content…
Carboxylic acids constitute of a carbonyl (C=O) and a hydroxyl (OH), both of which can form hydrogen bonds and allow carboxylic acids to be polar. As previously mentioned, carboxylic acids are more soluble than dicarboxylic acids. However, another trend that can be seen from Graph 1 is that the smaller carboxylic acids (made up of no more than 5 carbons) have greater solubility than those larger (made up of 6 or more carbons). This is due to the decrease in hydrophobic nature of the non-polar C-H and C-C bonds as there are less of them in smaller chains; this increases solubility. When oxygen forms a covalent bond with carbon and hydrogen, as is the case in carboxylic acid groups, a strong permanent dipole is created. This dipole allows hydrogen bonding between molecules of the carboxylic acid and the polar molecules of water. In smaller carboxylic acids, these hydrogen bonds are not broken and replaced by weaker Van der Waals dispersion forces as are in larger carboxylic acids. Thus, the smaller the carboxylic acid is, the higher is its…show more content…
It is important to note that accurate conclusions cannot be drawn from the graph as there is a limited number of data points. Nonetheless, the samples were separated when being graphed as otherwise there was no pattern in the lines. The blue line shows a decrease in solubility as molar mass increases in non-polar amino acids. Non-polar amino acids are hydrophobic and, thus, do not dissolve well in water, which explains their generally low solubilities. As molar mass increases, the solubility decreases due to the increase in hydrophobic nature of the non-polar C-H and C-C bonds as there are more of them in longer and larger chains. The orange line also shows a decrease in solubility as molar mass increases, however, it represents polar amino acids with no charge. Since the polar, uncharged amino acids are hydrophilic, it was expected that they would be more soluble than the non-polar amino acids. In fact, the hydrophilic nature is what allows its molecules to hydrogen bond with the water molecules. However, the graph shows otherwise; this may be because the polar, uncharged amino acids have overall larger molar masses than the non-polar amino acids and, for reasons previously mentioned, are not as soluble. In the case of the yellow and green lines representing polar amino

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