Deciphering Mixture Components Through Separation Techniques

Analysis/Conclusion
Based on our observations during the separation techniques and some speculation, we were able to identify eight components of our mixture: graphite from the filtration residue, Epsom salt from crystallization, water and acetic acid through distillation, red and orange dye, iron metal, marble chips, and sand.
To start with, the first separation technique we performed on the heterogeneous mixture was filtration. According to our observations of the residue, we believed graphite was one of the substances in the mixture. Graphite, a known ingredient used in pencils, is black or dark grey in color, like the dark spots on the filter paper (Figure 1B), and has the ability to leave marks on paper and other objects. Of the potential components given to us, only graphite possessed the ability to make a mark on other surfaces. This was supported by the smudges left behind on our finger and filter paper (Figure 1A, bottom filter paper) when we touched the residue.
Afterwards, we conducted crystallization to evaporate the liquid in an attempt to detect the presence of a salt. Before stating which of the potential

suspects we determined the salt to be, each of the potential substances are shown below to be referred to during the comparison.
Through contrast and the process of elimination, we determined the salt from crystallization (Figure 2B) to be Epsom salt.

By comparing the texture of each, we can immediately eliminated baking powder, chemically known as NaHCO3, because it had a finer texture and lacked the crystalline structure evident in Figure 2B. The remaining suspects would then be table salt or NaCl in Figure 2D or Epsom salt in Figure 2E. In continuing to compare crystal structures, table salt had a blocky, cubic crystal structure; whereas Epsom salt contained more irregularly shaped particles, most of which appeared to be pentagons. Figure 2B showed that the crystal structure of the salt was in no way cubic or regularly-shaped, eliminating it from the list of possible constituents. That would leave behind Epsom salt as the identity of the salt from

crystallization.
Following crystallization, we distilled the filtrate from Step 1. Although the first boiling point reached was 103.0°C (presumably a result of the thermometer touching the side of the glass or hot plate while it was dipped in the filtrate) we believed the identity of the first distillate to be water, for two reasons. First, the boiling point of 103.0°C was too large to be the boiling point of alcohol, with a difference of 16°C. If the first distillate was alcohol, then the percent error would have been 18%, too large of a margin between the accepted and experimental values. However, as water, it would only have a 3% error. Acetic acid would be a contender as well, with a percent error of 4%. Nevertheless, this possibility would soon be overturned when examined in more detail.
Upon closer inspection, the first distillate could not be acetic acid, because it had the highest boiling point out of the three potential liquids from the list of possible ingredients in the mixture. If the first distillate was acetic acid, then the second distillate must have a higher boiling point than it (above 107°C). This substance was not among the list of components; therefore, it could not be the second distillate, which would mean acetic acid, the substance with the highest boiling point of the three, could not be Distillate A. With alcohol and acetic acid eliminated, water was left behind; ergo, it is the first distillate from the distillation process, and one of the liquids in the heterogeneous mixture.
Because we were unable to finish distillating the filtrate, this portion of the analysis on the identity of the second distillate is conjecture. If we were allowed to continue the distillation, the temperature would have continued to rise until it reached the boiling point of the second distillate, after which we would have switched out the test tube containing the first distillate for an empty one, to contain the new distillate. Once the temperature reached the boiling point of the second substance, it would have remained constant, boiling the liquid so that it would evaporate into a gas, which would have condensed back to a liquid into the test tube in the beaker of ice via a tube connecting the receiving flask (test tube) and flask of mixture (filtrate from the filtration process). Out of the two remaining possible liquids, alcohol (boiling point 87°C) and acetic acid (boiling point 107°C), it is most likely that the second distillate is acetic acid. If it was alcohol, it would have reached the boiling point of 87°C first, instead of 103.0°C, because as the temperature rises from the original temperature of the filtrate (23.0°C), it would hit the lower boiling point first. The fact that the temperature exceeded 87°C would suggest that the second distillate would not be alcohol. Rather, it is most likely acetic acid because its boiling point had not been reached yet.
Similarly, chromatography was another one of the separation techniques we were unable to perform, so this section of the analysis on the possible dyes and pigments is speculation as well. Supposing that we were able to continue with the experiment, we would have performed chromatography like so (see Figure 7 for a similar setup): First, we would have made an ink spot with the filtrate on the chromatography paper; then suspended the paper over the solvent (water) with a pencil lying across the mouth of a beaker. The tip of the paper would be dipped in the water, but the ink spot would not. Then, it is only the matter of waiting for the water to rise via capillary action and separate the pigments in the mixture, which appear as differently colored bands on the chromatography paper. We would then calculate the Rf factor of the pigments using the formula, Rf = distance traveled by pigment ÷ distance traveled by solvent (water).
Because we were unable to perform the chromatography, the justifications for the color of the dyes were dependent on what we had observed in previous steps. We believed two of the pigments in the heterogeneous mixture to be red and orange dye. Based on the color of the filtrate alone (see Figure 1), we could see that the filtrate was a red-orange color, making the presence of red and orange dye very likely. Moreover, when we filtered the mixture, we noticed that the filter paper was stained a light red color (see Figure 1A and Figure 1B), which would support our belief that one of the dyes were red. Additionally, during the crystallization process, the filtrate left orange rings around the side of the evaporating dish, with each successive ring darkening in color to a red-orange color. The salt left over in the dish was an orange color as well (Figure 2A), though it looked brown under a microscope (Figure 2B), hinting at the presence of other pigments. Also, during the evaporating process, the boiling filtrate appeared redder than it had been before (Figure 2). Referring to our initial observations of the mixture during filtration and crystallization alone, we determined two of the dyes to be red and orange. Although we found no hint of other dyes in the mixture beside the two throughout the rest of the separation techniques, it is very possible that there were other pigments that remained undetected.
Meanwhile, while we were waiting for the filtrate to boil, we attempted to distinguish the constituents found in the sediment of the mixture. Judging by the size and color of the pebbles, we recognized one of the components of the mixture as marble chips. Owing to the fact that the pebbles were not lustrous, a known property of metals, we were able to eliminate all the remaining metals from the list of potential substances. Clearly, the pebbles were a solid, and lacked the crystalline structure of salts, leaving gravel, marble chips, and sand as suspects. Among the three, the particles in sand were too small and fine to be a possibility, which narrowed down the list to either gravel or marble. Referring to Figure 6, the pebbles were white with orange streaks running through them, suggesting that they were sedimentary, and contained little flecks of crystals dispersed throughout. In a comparison between marble and gravel, marble is the result of sedimentary rocks undergoing metamorphism, typically containing carbonate crystals as an effect of the heating and compression; gravel, on the other hand, is unconsolidated, weathered rock material. According to our observations, the rocks were marble because they displayed streaks indicative of sedimentary rocks, and contained flecks of white crystals that corresponded with those that occurred from recrystallization during metamorphism. On that account, we decided that the rocks were marble chips.
From there, we attempted to discern the substances that formulated the finer remains that settled at the bottom of the suspension. Since iron metal was the only magnetic metal in the list, we believed one of the elements in the mixture to be iron metal. As seen in Figure 4, the black grains stuck to the magnet when the two came in contact with each other. Iron is well-known for its magnetic properties, which made it the prime suspect for the black grains. Zinc and lead, the other two metals, are diamagnetic, meaning they repel magnets. Evidently, their magnetic properties are the opposite of our observations on the interaction between the black grains and magnet. Consequently, we arrived at the conclusion that the black grains were iron metal due to its attraction to the magnet.
Eventually, we reached the last substance. By definition, sand is a heterogeneous mixture of eroded rocks and minerals, finer than gravel, but not silt. Its composition, and therefore, color, varies depending on location, but it is generally tan or brownish. Of the solids we were left with (lead, zinc, gravel, or sand), we were able to exclude lead and zinc because they were not heterogeneous substances; lead and zinc are elements, pure substances composed of only one type of atom. Gravel was too coarse (> 2.0 mm); its particles would have been greater than the accepted range for sand (1/16 mm to 2.0 mm). Thus, according to the extensive, physical property of size, sand was the final substance we were able to identify in our mixture.
To sum, we used the separation techniques and some conjecture to identify the substances in the mixture. Graphite was detected in the residue when we performed filtration, in accordance with its ability to make marks on other objects. The presence of Epsom salt was identified by comparing the crystal structures of known salts to the one found in crystallization. Distillation yielded water and acetic acid, both supported by their boiling points. Because we were unable to execute chromatography, our detection of red and orange dye were founded on previous observations from the crystallization process and the mixture itself. Marble’s determination was the outcome of a comparison based on its color and size, whereas iron was defined by its magnetic properties. Finally, sand was pinpointed through process of elimination. Altogether, we identified eight components of our mixture: graphite, Epsom salt, water and acetic acid, red and orange dye, iron metal, marble chips, and sand.