Question

Paper chromatography lab experiment. (color dye)

in the solvent system that you use for analyzing your unknown a)name the important intermolecular forces acting between the dye and the solvent and b)the dye and stationary phase for (i) the dye with the largest Rf value (ii) the dye with the smallest Rf value. comment on the relative important of the types of the forces that result in observe Rf value. c) what statical test could you apply to give some quatitation of your confidence that your known and unknown have the same Rf value?

Answer 1

Rf =distance traveled by the spot /distance traveled by the solvent front

Rf value is characterized as the proportion of the separation moved by the solute (i.e. the color or shade under test) and the separation moved by the dissolvable (known as the Solvent front) along the paper, where both separations are measured from the basic Origin or Application Baseline, that is the point where the example is.

By definition, Rf qualities are constantly under 1. A Rf estimation of 1 or excessively near it implies that the spot and the dissolvable front travel near one another and is in this manner inconsistent. This happens when the eluting dissolvable is excessively polar for the example. Another run must be made utilizing a less polar dissolvable to enhance the division. In like manner, if the spot scarcely moves and its voyaged separation is almost zero, there has presumably been no possibility for division. This happens when the eluting dissolvable is not sufficiently polar for the specimen. Another run must be made utilizing a more polar dissolvable to enhance the division.

It was specified before that the extremity of the example and its rate of development are conversely related. The more polar spot ventures slower, and the less polar spot voyages speedier. Rf values, then again, are specifically related

to the rate of development. The quickest moving spot has the most elevated Rf esteem.

Subsequently Rf qualities and extremity are conversely related. The spot with the most noteworthy Rf esteem is the minimum polar (speediest moving), and the spot with the least Rf esteem is the most polar (slowest moving).

Rf qualities are much of the time used to analyze a known and an obscure substance to figure out whether they are the same. For whatever length of time that their spots are run all the while on a similar plate, the contention can be made that if their Rf qualities are the same, and if the general appearance of the spots is the same, then they are the same compound.

Rf values rely on upon:

• The polar way of the dissolvable utilized

• Polar nature of the stationary stage

• Polar nature of the example

• Conditions of the examination

Rf qualities are along these lines not precisely reproducible starting with one investigation then onto the next, regardless of the possibility that an exertion is made to convey them under precisely the same. At the point when looking at least two substances, they should be run at the same time on a similar plate or the examination is invalid.