Finding The Identity of Unknowns

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SUMMARY

The discussion focuses on identifying two unknown liquids in a chemistry class using various methods. Key techniques mentioned include determining boiling points, conducting density tests, and performing solubility tests. Participants suggest utilizing textbooks and reference materials, such as the CRC Handbook of Chemistry and Physics, to assist in identifying the substances. The effectiveness of color tests is debated, with a consensus that they should be used in conjunction with other methods for accurate identification.

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  • Understanding of boiling point determination
  • Knowledge of density measurement techniques
  • Familiarity with solubility principles
  • Access to the CRC Handbook of Chemistry and Physics
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  • Research methods for determining boiling points of liquids
  • Learn about density measurement techniques in chemistry
  • Study solubility tests and their applications
  • Explore the CRC Handbook of Chemistry and Physics for reference materials
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Chemistry students, educators, and laboratory technicians seeking effective methods for identifying unknown substances in liquid form.

don123
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For my chem class my teacher is going to give us 2 unknowns and we have to find out their identity. How would you do this?

I figured that you would heat the liquids to figure out their boiling point and then look in the book (she'll let us use the books) to figure out the substaNce.

I could also do the color test lab but I don't think that it is very effective.

BTW I posted this in Chem section and didn't get respons so I figured I'd try here.
 
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don123 said:
For my chem class my teacher is going to give us 2 unknowns and we have to find out their identity. How would you do this?

I figured that you would heat the liquids to figure out their boiling point and then look in the book (she'll let us use the books) to figure out the substaNce.

I could also do the color test lab but I don't think that it is very effective.

BTW I posted this in Chem section and didn't get respons so I figured I'd try here.

Hello Don.
Surely you must have some general guidelines and have at least some idea what it is right? Generally you'll have some qualitative scheme to "narrow down" the possible candidates. Have you been given this? Is is both two liquids? Both organic? Polar, non-polar? Volatile? I don't know about the heating up part. You know, you can just wave your hand over it carefully to get just a tiny and I mean tiny wiff of it. You know basic rule of Chemistry is NOT to put your nose to it right? Well, I don't know what you know. Smells like alcohol, we're on our way.

Edit: I think color test are effective if done in a methodical way and used with other evidence.
 
Last edited:
don123 said:
For my chem class my teacher is going to give us 2 unknowns and we have to find out their identity. How would you do this?

I figured that you would heat the liquids to figure out their boiling point and then look in the book (she'll let us use the books) to figure out the substaNce.

I could also do the color test lab but I don't think that it is very effective.

BTW I posted this in Chem section and didn't get respons so I figured I'd try here.
Boiling point is one good indicator. The density is another. You can also do solubility tests (is the unknown liquid dissolved and completely mixed with the solvent or do they form layers, etc.). In fact, I imagine that either your textbook or lab book has a table that lists all three characteristics (boiling point, density, & a solubility chart). If not, I'm sure the lab has a reference that does (the CRC book is a good reference - even if I can't remember it's full name, I think it normally has a dark red cover :smile: ).
 

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