Question: A compound melting at 134 degrees C was suspected to be either aspirin (mp 135C) or urea (mp 133C) Explain how you could determine whether one of these two suspected compounds was identical to the unknown compound without using any form of spectroscopy.
This seems the same type of problem as my other most recent posting. It seems that the identity could be determined by a mixed melting point procedure if you had aspirin and urea available. A narrow melting point range would verify the substance and eliminate the other.
Sheryl
That's right. Another solution would be odor. Most aspirin smells faintly of acetic acid, expecially in moist air. It hydrolyzes. Urea, with most air and hydrolysis, smells like NH3. Urea is a base, aspirin is an acid so that will distinguish them also. But the mixed melting point is the correct answer here since that is what you are studying.
The unknown compound could be aspirin,this can only happen if the aspirin contains a little impurity and the heating rate is moderate,then its possible for aspirin to melt at a temperature a little less than 135 degree celcius.
Also,the unknown compound could also be Urea(132-133) if a pure sample of urea is heated at a high rate thus a little addition to the thermometer value when it reads the melting point of urea (ie 135 degree celcius).
Well, well, well, Sheryl, it looks like you've got a nose for chemistry! Using your olfactory prowess to differentiate between aspirin and urea is indeed a clever idea. Acetic acid, with its distinctive scent, would sneakily reveal the presence of aspirin, while urea would unleash the pungent smell of ammonia. It's like a battle of the odors, Sheryl! But hey, let's not forget about the mixed melting point procedure you mentioned. It's like a melting pot of compounds, where the true identity of our mystery compound can be uncovered. So, whether you're sniffing away or melting your way to the answer, you've got two hilarious and valid ways to solve the case, my inquisitive friend! Keep up the good work!
Yes, the mixed melting point procedure would be the most effective way to determine the identity of the unknown compound without using any form of spectroscopy. Here's how you could perform the mixed melting point procedure:
1. Obtain a sample of the unknown compound and a small amount of each of the suspected compounds (aspirin and urea).
2. Prepare separate samples of the suspected compounds by crushing them into a fine powder.
3. Take a small amount of the crushed suspected compound and mix it with an equal amount of the unknown compound. Make sure to thoroughly mix the two compounds together.
4. Place a small portion of the mixture into a capillary tube or melting point apparatus.
5. Heat the mixture gradually and observe at what temperature it starts to melt. Record this temperature.
6. Compare this melting point with the known melting points of aspirin (135 degrees C) and urea (133 degrees C).
7. If the observed melting point matches the known melting point of aspirin (within a narrow range), then the unknown compound is likely aspirin. If it matches the known melting point of urea (within a narrow range), then the unknown compound is likely urea.
8. If the observed melting point does not match the known melting points of either aspirin or urea, then the unknown compound is not identical to either of the suspected compounds.
Remember to perform the mixed melting point test multiple times using fresh samples to ensure accurate results.
Yes, you are correct. One way to determine the identity of the unknown compound without using any form of spectroscopy is by performing a mixed melting point procedure. Here is how you could do it:
1. Obtain samples of both aspirin and urea, which have known melting points of 135 degrees C and 133 degrees C, respectively.
2. Take a small amount of the suspected compound and mix it in equal proportions with a small amount of either aspirin or urea.
3. Carefully heat the mixture and observe the temperature at which it begins to melt.
4. If the mixture melts at a temperature close to 135 degrees C, then it is likely that the unknown compound is aspirin. On the other hand, if the mixture melts at a temperature close to 133 degrees C, then it is likely that the unknown compound is urea.
5. Repeat this mixed melting point procedure with the other compound (aspirin or urea) to confirm the results.
By comparing the melting point of the mixture with the known melting points of aspirin and urea, you can determine the identity of the unknown compound. If the melting point range of the mixture matches that of one of the known compounds, it would indicate that the unknown compound is identical to the one with the matching melting point range.