Chemistry coursework, identifying unknown chemicals

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SUMMARY

This discussion focuses on strategies for identifying six unknown chemicals from a provided list of eight, utilizing limited reagents and test techniques. The participant plans to start with a litmus paper test to categorize the chemicals as acidic or alkaline, followed by specific tests such as the iodoform test and 2,4-dinitrophenylhydrazine (2-DNPH) to identify carbonyl compounds. The suggested approach emphasizes creating a flow chart to streamline the testing process, beginning with 2-DNPH to differentiate between carbonyls based on positive or negative results. The participant also seeks clarification on the reactivity of sodium hydrogen carbonate with various compounds.

PREREQUISITES
  • Understanding of organic chemistry functional groups, particularly carbonyls.
  • Familiarity with qualitative analysis techniques in chemistry.
  • Knowledge of specific reagents such as NaOH, H2SO4, and 2-DNPH.
  • Basic skills in creating flow charts for experimental procedures.
NEXT STEPS
  • Research the mechanism and application of the iodoform test for identifying ketones and aldehydes.
  • Learn about the qualitative analysis of functional groups using 2,4-dinitrophenylhydrazine (2-DNPH).
  • Investigate the pH characteristics of nitriles, specifically benzonitrile and ethanamide.
  • Explore the reactivity of sodium hydrogen carbonate with various organic compounds beyond carboxylic acids.
USEFUL FOR

Chemistry students, educators, and laboratory technicians involved in organic chemistry coursework and qualitative analysis of unknown substances.

alias25
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i have to do the plan of my chemistry coursework by monday...

im having trouble with where to start..i have to identify 6 unknown chemicals. I am given a list with 8 chemicals that contains the name of 6 unknowns that i have and 2 extras.

im thinking of starting with a litmus paper test for alkaline/acidic. for all the chemicals and grouping them.
(we have limited reagents/test techniques we can use..
we have NaOH, H2SO4, NaHCO3, iodoform test, 2,4-dinitrophenylhydrazine, tollen's reagent. and water of course and bunsen burner)

any help would be appriciated thank you.
 
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im thinking i could do an iodoform test on them all firslty instead of acid/alkali to test for a CH3 group next to C=O group, is that a good move? bad?
because i, not sure where to go from saying these bunch of chemicals are acidic, i could then do an iodoform test on them...but that's silly if the other bunch of chemical, the alkaline ones have compounds with C=O next to CH3 as well, then i could do iodoform on them too.
i have to reduce the number of test i apply to these chemicals, so i can't just preform all tests on all chemicals.
 
I don't know about the PH test but I've done the general ID procedure several times - forgotten what it's called actually. My best advice would be to draw up a flow chart that runs over 2 odd pages.

I'll start you off: begin by adding 2-DNPH (to all of them until you get a positive) and that gives you either a POSITIVE or a NEGATIVE (as with any test). If its a POSITIVE you've got your carbonyl compounds, then continue your flow chart to differentiate between the carbonyl compounds. From the NEGATIVE route, go on to test for other compounds using their various tests.

Summing up:

1. Add 2-DNPH
If Positive -> Continue flow chart to differentiate between carbonyls
If Negative -> Begin other tests.
 
but my chemistry teacher advised to start with ph tests...but ill think about it, would you know if sodium hydrogen carbonate would react with anything other than carboxylic acid form that list?

1)can some one tell me the ph of nitriles in particular benzonitrile?

2)0and ethanamide? please i can't find anything by googling.
 
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