An unknown sample was known to be either cinnamic acid(m.p 133 centigrade),urea(m.p 133-135C), or malonic acid(135-136C).Given a sample of the unknown and samples of each to these three compounds,briefly indicate how you could establish the identity of the unknown through m.p determination alone.
NB: For you critics out there, I have an answer(idea). just wanted to get more views as I could be wrong. I try very hard to do my assignments without having to disturb other people. So be lenient with any negative comments or more, if you don't want to answer, pls do not criticise.
2006-10-10 04:55:20 · 6 answers · asked by obiora c 2 in Science & Mathematics ➔ Chemistry
First of all you are not allowed to use two different IDs and answer your own question. Do you want to be reported?
If you have an answer and want to double-check it, provide it as "additional details".
Actually the answer is rather simple. You have a sample which corresponds to a PURE substance but you don't know to which of the three and also have labelled samples of each compound. So you just observe simulatneously the melting of the unlabelled and the labelled samples (if I remember correctly each appartus has slots for 3-4 samples). The identity of the unlabelled sample will be that corresponding to the labelled sample that melted at the same time as the unknown. You don't even need a thermometer...
If the sample is not a pure substance then the mps are so close that you won't be able to say what it is based only on the mp.
2006-10-10 07:38:42 · answer #1 · answered by bellerophon 6 · 0⤊ 0⤋
Thanks to anyone that tried/will try to answer this question.
My answer thus: One can establish the identity of the unknown by using a mixed melting point method. Since an impure sample will have a higher temp. range. When you perform the experiment in the form:-unknown+cinnamic acid=x value of M.P
unknown+urea=y value of M.P and unknown+malonic acid=z value of M.P, from the three mixtures one will contain the same sample as the known, therefore producing the known M.P temp. range while the others will be higher as they are impure. With this, you can finally establish the identity of the unknown sample through M.P alone.
NB:I asked the question. Thanks once more for your efforts
2006-10-10 06:02:07 · answer #2 · answered by Tochukwu I 1 · 0⤊ 0⤋
As the melting points of all the three compounds lie in a close range and it might be possible that ur sample could show u a range of melting point like133-136 or134-136 or anything, then it will become difficult to find out the identity
Anothe problem is that all the MP lie between each other's range of error, so ur unknown compuond could point out towards a wrong compound.
WAT I WILL DO IS
FIND OUT THE FUNCTIONAL GROUPS PRESENT IN THE UNKNOWN BY IR SPECTROSCOPY
That would solve the problemo
2006-10-10 09:39:18 · answer #3 · answered by metallixan 2 · 0⤊ 0⤋
If the unknown is impure the melting points alone is not enough to identify it, since the difference in the melting points of three compounds are close to each other.
Compare the shape of crystals of three compounds and look at the difference between them , and which one is look like the unknown, try the solubility of the three compounds and the unknown with water, then look at the melting point.
2006-10-10 05:16:31 · answer #4 · answered by basimsaleh 4 · 1⤊ 0⤋
you will possibly basically soften something and take its temperature because it melts. something is at its melting temperature on the factor there remains stable remember in a pool of the liquid. of course the easily approach and the equipment used may be hugely distinctive while looking the melting factor of drugs that have hugely distinctive melting factors IE water and copper.
2016-12-08 12:12:12 · answer #5 · answered by kleckner 4 · 0⤊ 0⤋
A melting point is when something melts.
Like Ice cream on a very HOT day.
2006-10-10 05:14:31 · answer #6 · answered by **tomtom 5 · 0⤊ 0⤋