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1. Provide a general discussion of the solubility/miscibility behavior observed in procedure A-D. For part A of the procedure we worked with the solubility of solid compounds in various solvents. The three solid compounds that were worked with during this procedure were benzophenone, malonic acid, and biphenyl. These three solids were then mixed with water (highly polar), methyl alcohol (intermediately polar), and hexanes (nonpolar). When benzophenone is mixed with water the results turned out to be insoluble because benzophenone is a pure hydrocarbon, which are very insoluble in water.
When benzophenone was mixed with methyl alcohol, it was soluble because Methanol can hydrogen bond to the carbonyl oxygen of benzophenone. When benzophenone was added to hexanes it was partially soluble because “likes dissolve likes” benzophenone is polar and hexane in non polar. When the next compound, malonic acid was combined with water and with methyl alcohol it turned out to be soluble in both cases. However when malonic acid was combined with hexanes it was in soluble because Malonic acid is polar where as hexane is nonpolar. When the final compound, biphenyl was added to water it was insoluble because biphenyl is a non-polar molecule.
Biphenyl was partially soluble when it was added to methyl alcohol but when hexane is added it is soluble because both are non-polar and “likes dissolves likes”. For part B of the procedure we worked with the solubility of various alcohols in water and hexane. The three alcohols we used were 1-octanol, 1-butanol, and methyl alcohol. When 1-octanol was added to water it is insoluble because the longer the carbon chain, the more water is repelled. However when 1-octanol was added to hexane it was soluble because it is a polar molecule being that it is an alcohol.
When 1-butanol is added to water it is partially soluble because 1-butanol slightly polar. Which means that it was soluble in hexane. When methyl alcohol was added to water it was soluble because the polarity of the hydroxyl group is stronger than unpolartiy of the Carbon chain. There for when methyl alcohol was added to hexanes it was insoluble. For procedure C we determined the miscibility of solvents. For water and ethyl alcohol it was miscible because the alcohol will mix with both polar and nonpolar compounds. For water and diethyl ether it was immiscible because diethyl ether is nonpolar and less dense that water.
For water and methylene chloride it was immiscible because water has a lesser density than methylene chloride. For water and hexanes it was immiscible because hexans is less dense than water. For Hexanes and methylene chloride it was miscible because both have very weak Vander wall forces. For hexanes and diethyl ether it was miscible because hexane is non polar they lack intermolecular attractions. This is the same case for diethyl ether and methylene chloride and diethyl ether and ethyl alcohol. Finally for part D we worked with the solubility of organic acids and bases.
We used two compounds, benzoic acid and ethyl 4-aminobenzoate, which we mixed with water, 1. 0M NaOH+ 6. 0MHCl, and 1. 0M HCl with 6. 0M NaOH. Both were tested for their solubility in water and both turned out to be insoluble due to the fact that they are either a strong acid or strong base. When 1. 0M NaOH was added to the benzoic acid it became soluble because NaOH is a strong base, which in turn causes benzoic acid to turn into and weak base with the byproduct of Na and H2O. When the HCl was added to the benzoic acid it precipitated because HCl is a strong acid.
When Ethyl 4-aminobenzoate was added into 1. 0M NaOH it was insoluble because they were both basic. But when Ethyl 4-aminobenzoate was added to 1. 0M HCl it was soluble and turned the Ethyl 4-aminobenzoate into a weak acid and water soluble. Then when the 6. 0M NaOH was added again the ethyl 4-aminobenzoate precipitated. 2. In Reference to Pavia, Technique 10, pp. 638-644, briefly discuss the principles of solubility/ miscibility. Solubility is the behavior of a solute either getting dissolved (soluble) or not dissolving (insoluble) in solvent. Solubility is always expressed in g/L ot mg/ml of solvent.
It is also important to remember that for solubility there are many degrees of measurement. For miscibility there are only two degrees of measurement; Miscible and immiscible. Miscible will mix homogeneously and will be observed by seeing one layer. Immiscible compounds won’t mix homogenously and will form two layers. There is one essential difference to understanding the difference between solubility and miscibility. For solubility there are many degrees of measurement, for example a compound can be soluble, partially soluble or insoluble. For miscibility there are only two degrees of measurement, miscible and immiscible.