Question

As an update to my previous question. i have a lab practical coming up where we have to identify 3 unknow solutes and I’m not sure as to how to go about doing so. These are the parameters

“You can do reactivity tests, spectrophotometry, titrations, pH, freezing point depression, density, and many more

Density tests may prove to be extremely difficult when dealing with substances that partially dissolve. Therefore, be careful if you choose to use this procedure

Be sure you understand what the wavelength of the spectrophotometer means if you choose to use that test

NO flame tests.”

Can someone explain how to go about this?

the question would be how do I use these to find the identity of an unknown.

This isnt like a homework question or anything. Im just wondering the best way to identify an unknown solute given these methods

Answer 1

Reactivity tests and depression in freezing point tests can help you in finding out unknown solute qualitatively. Whereas titration, spectrophotometry gives you information about the amount of the solute present. Freezing point experiment gives you molar mass of the solute which in turn you can confirm it.

Reactivity tests are vast and differs for every other ion to be found out. Also titrations have different procedures for different compounds. I can't be specific without knowing what exactly you are trying to find out.

Spectrophotometry can be used to find out concentration of the Solute by series dilution of the sample along with the unknown sample . By taking absorption value for each concentration you can find out unknown concentration using graph of conc vs absorption.