A student who was isolating aspirin stopped the experiment after the filtration step with alumina. One week later, the methanol was evaporated and the experiment was completed. The melting point of the aspirin was found to be 110-115 degress Celsius. Explain why the melting point was low and why the melting range was so wide.
My Answer:The melting point was low and the melting range was so wide because the aspirin partially decomposed. Therefore, it became impure and caused the melting range to widen. Due to the partial decomposition, the carbon backbone broke down some, which allowed the student’s aspirin to melt at a lower temperature.
Is this correct? Please Help!
<<My Answer:The melting point was low and the melting range was so wide because the aspirin partially decomposed.>> this seems reasonable. Was the aspirin allowed to stand in the methanol? What happens if you allow an ester to stand in a large excess of an alcohol? Also what happens if you allow a carboxylic acid to stand in an excess of an alcohol?
<>Therefore, it became impure and caused the melting range to widen.>> Agreed.
<< Due to the partial decomposition, the carbon backbone broke down some,>> you are guessing here!! what are the possible side products?
You're on the right track, but let me add a touch of humor to explain it better:
Well, it seems like the student's aspirin went through some unexpected changes! You see, aspirin is supposed to have a specific melting point, but in this case, it decided to be a rebel and mix things up a bit. It partially decomposed during the filtration step with alumina, which means it broke down into some other substances.
Now, when a compound decomposes, it forms impurities, and these impurities can mess with the original melting point. It's like inviting some uninvited guests to a party and then wondering why the atmosphere became strange. These impurities widened the melting range, so instead of having a narrow range of temperatures at which the aspirin melts, it now had a wider range of 110-115 degrees Celsius.
So, in conclusion, the low melting point and wide melting range of the aspirin happened because it decided to undergo partial decomposition, bringing some unexpected party crashers along and resulting in a melting point that went all over the place. Silly aspirin!
Your answer is partially correct. The low melting point and wide melting range of the aspirin could indeed be attributed to the partial decomposition of the compound. However, it is important to include the effect of impurities on the melting point in your explanation.
When a compound is impure, it will have a lower and wider melting point range compared to a pure compound. Impurities present in the aspirin, possibly remnants from the experiment or contaminants introduced during the isolation and purification process, can lower the melting point and broaden the melting range.
Furthermore, as you mentioned, the partial decomposition of aspirin can also contribute to the lower melting point. Aspirin is sensitive to heat, and excessive heating during the evaporation of methanol or the filtration step with alumina could lead to the breakdown of the compound.
Therefore, to summarize, the low melting point and wide melting range of the aspirin can be explained by both the partial decomposition of the compound and the presence of impurities.
Your explanation is partially correct, but it does not provide a complete understanding of why the melting point was low and why the melting range was wide. Here's a more detailed explanation:
The low melting point and wide melting range of the aspirin can be attributed to the presence of impurities and the partial decomposition of the compound. Aspirin is a relatively stable compound at room temperature, but it can decompose under certain conditions.
During the isolation process, filtration with alumina was performed to separate the aspirin from other impurities. However, it is possible that some impurities remained in the aspirin sample, which can lower the melting point and contribute to a wider melting range. These impurities may have different melting points, causing the melting range to be broader.
Furthermore, the time gap between the filtration step and completing the experiment could have allowed for some decomposition of aspirin. The methanol used for the filtration step was evaporated, which potentially exposed the aspirin to air, moisture, or other factors that can promote decomposition. As a result, the chemical structure of aspirin may have partially broken down, leading to a lower melting point and a wider melting range.
In summary, impurities and partial decomposition of the aspirin are the likely reasons behind the low melting point and wide melting range observed in this experiment.