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Where can I get the standard Rf value?

Posted: Thu Jun 26, 2014 8:11 am
by SYLIM
Hello, I'm a form six student this year. My group and I were given a task on chemistry project, which we were asked to identify the chemicals that cause the existence of colours on flowers. (Project Theme: Investigating the chemical and/or physical properties of naturally occurring substances)
The method we used is by paper chromatography, we had extracted its pigments out using 0.2mol and 0.5mol of NaOH on chromatography papers. We plan to compare and analyze the results by using different mol of solvents in our project.

What matter is we couldn't find any standard Rf value for the solvents (NaOH) we used though we have been searching for it in the internet for weeks. We asked our chemistry teacher and she answered that what we have to do is continue searching for it in the internet. But what we found out was, there is no such standard rf values as the results may vary due to the environmental factors.

So.. Can anyone tell me where can I get the standard Rf value or any books that I can refer to? We are unable to complete the project without the standard rf value as we fail to identify the chemicals that cause the existence of colours. :(

Thank you

Re: Where can I get the standard Rf value?

Posted: Thu Jul 03, 2014 8:54 am
by deleted-71487
I don't exactly know what you would mean by the Rf of the solvents. Rf is a ratio defined as (migration distance of substance)/(migration distance of solvent).

The only coherent meaning I can think of would imply that it's 1, by definition.

Or are you asking about something different?