Chemistry coursework, identifying unknown chemicals

In summary, the first step is to add 2-DNPH to each of the chemicals to test for carbonyls. If a chemical results in a positive or negative with the addition of 2-DNPH, the flow chart will help you differentiate between the various carbonyl compounds. Next, test for other compounds using the various tests mentioned in the summary.
  • #1
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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  • #2
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.
 
  • #3
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.
 
  • #4
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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1. What is the purpose of identifying unknown chemicals in chemistry coursework?

The purpose of identifying unknown chemicals in chemistry coursework is to develop practical skills in analytical chemistry. It involves using various techniques and methods to determine the identity and composition of unknown substances, which is a crucial aspect of the scientific method.

2. What are some common techniques used to identify unknown chemicals?

Some common techniques used to identify unknown chemicals include spectroscopy, chromatography, and titration. Spectroscopy involves using a spectrophotometer to measure the absorption or emission of light by a substance. Chromatography involves separating and analyzing the components of a mixture through their different rates of movement. Titration is a method of determining the concentration of a substance in a solution by adding a known amount of another substance.

3. How do scientists ensure accuracy and reliability when identifying unknown chemicals?

Scientists ensure accuracy and reliability when identifying unknown chemicals by following strict protocols and procedures. This includes carefully measuring and recording data, using standardized solutions and equipment, and repeating experiments multiple times to ensure consistent results. It is also important for scientists to have a thorough understanding of the principles behind each technique and to use proper safety precautions.

4. Can unknown chemicals be identified with 100% certainty?

No, unknown chemicals cannot be identified with 100% certainty. There is always a margin of error and uncertainty in scientific experiments, and identifying unknown chemicals is no exception. However, scientists can use a variety of techniques and methods to narrow down the possibilities and make an educated guess about the identity of a substance.

5. How can the knowledge gained from identifying unknown chemicals be applied in the real world?

The knowledge gained from identifying unknown chemicals can be applied in various industries, such as pharmaceuticals, food and beverage, and environmental testing. It can also be useful in forensic investigations, where identifying unknown substances can provide valuable evidence. In addition, understanding the properties and behavior of different chemicals can help scientists develop new products and technologies.

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