A student sets up a paper chromatography experiment and places a spot of food dye on the origin. They remove the paper after 6 minutes and the solvent has moved 4.0 cm and a blue spot has moved 3.0 cm. The student runs the experiment again under identical conditions, however they leave experiment to run for 12 minutes. The solvent moved this time moved 6.0 cm. What distance did the blue spot move in this experiment?

Question

BlackTom AI · Accepted Answer

A key idea in paper chromatography is that the relative position of a compound to the solvent front is described by the Rf value, which remains constant under identical conditions. In the first run, the solvent front moved 4.0 cm and the blue dye moved 3.0 cm, giving an Rf = 3.0 / 4.0 = 0.75. If the second run is done under the same conditions, the dye should travel a distance proportional to the solvent front, so the expected blue spot distance is 0.75 × 6.0 cm = 4.5 cm.

Option a. 4.5 cm: This aligns with the constant Rf value method, making it the mathematically consistent choice given the data and assumptions.

Option b. 1.5 cm: This would correspond to a much smaller fraction of the solvent front than observed initially (1.5/6.0 = 0.25), which contradicts the same-Rf principle under identical conditions.

Option c. 3.0 cm: While this matches the initial distance in the first run, it does not scale with the increased solvent front distance in the second run, violating the idea that the dye’s movement is proportional to the solvent front under consistent conditions.

Option d. 6.0 cm: This would indicate the dye moved as far as the solvent front itself, which would imply an Rf of 1.0. Since the initial Rf was 0.75, this would be inconsistent with the observed relationship between solvent front and dye movement in the first run.

View Explanation

Log in for full answers

Similar Questions

Three samples containing amino acids are analysed using paper chromatography. Sample 1 contains alanine only. Sample 2 contains glycine only Sample 3 contains equal amounts of two unknown amino acids. The resulting chromatogram is shown below. The Rf value for alanine is

Three samples containing amino acids are analysed using paper chromatography. Sample 1 contains starting material. Sample 2 contains the reaction mixture. Sample 3 contains the product. The resulting chromatogram is shown below. From the chromatogram it could be concluded

Applying paper chromatography to separate the four substances below indicate where each substance will end up, starting from the bottom of the paper. (MW = Molecular Weight) a. Midazolam, MW= 525.77 b. Niridazole, MW= 214.20 c. Propiomazine, MW= 440.40 d. Streptomycin, MW= 681.57

In a consumer society, many adults channel creativity into buying things

Economic stress and unpredictable times have resulted in a booming industry for self-help products

People born without creativity never can develop it

More Practical Tools for Students Powered by AI Study Helper

Homework AI Solver

Stylized AI Paper Writer

Plagiarism Checker Assistant

Citation AI Academic Writing Tool

In-Class Translation Assistant

AI Note Generator

AI Quiz Answers

Past Exam Questions from University Test Bank

Smart Practice Assistant

Adaptive Practice

Making Your Study Simpler