Which of the following molecules will have the highest rf value when studied with thin-layer chromatography using a silica plate?
a. ch3ch2ch2ch2ch3
b. hoch2ch2ch2ch3
c. hoch2ch2ch2oh
d. hoocch2ch2ch3

A. CH3CH2CH2CH2CH3

Explanation:

The silica in the plate is polar and contains hydroxil groups in its surface.

Compound B, C, are polar containing hydroxyl gropus and compound D is a carboxylic acid which is polar. It follows then that these compounds will be retained more strongly than the non polar hydrocarbon compound CH3CH2CH2CH2CH3.

Since the retention factor, Rf, is defined as the distance travelled by the solute divided by the distance travelled by the solvent, we can deduce that compound A. CH3CH2CH2CH2CH3 will travel farthest and have the highest Rf.

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e