Forensic Science: Chromatography

What does the following Chromatogram tell you about the substance's make-up?

• The substance is pure

• The substance is a mixture

• The substance is insoluble in the mobile phase

• The substance is from a yellow pen

Tags

NGSS.MS-PS1-2

What is the Rf value of the purple dot?

• 0.60

• 3.00

• 2.40

• 0.70

When a substance has a high attraction to the mobile phase how does that effect its movement on the chromatography paper?

• The substance will move further

• The substance will not move

• The substance will move a short distance

• The substance will move slowly

What does it mean if the substance does not move on the chromatography paper?

• It is soluble in the mobile phase

• It is soluble in the stationary phase

• It is insoluble in the stationary phase

• It is insoluble in the mobile phase

What does a high Rf tell you about the substance's relationship to both the mobile and stationary phase?

• High attraction to mobile, low attraction to stationary

• High attraction to mobile, high attraction to stationary

• Low attraction to mobile, low attraction to stationary

• Low attraction to mobile, high attraction to stationary

What is the Rf value of the red dot?

• 0.60

• 2.00

• 0.40

• 0.20

Can we determine what a substance is if we know its Rf value, but don't know what mobile phase it was in?

• Yes because Rf values are intensive properties

• Yes because it is a calculation

• No because the Rf value does not tell us anything

• No because the Rf value is specific to both the substance and the mobile phase it is placed in

What is the proper way to hold a piece of chromatography paper?

• On the face

• By the sides

• On the line

• In the center

What does an Rf of 0.20 tell you about the substance's relationship to both the mobile and stationary phase?

• High attraction to mobile, low attraction to stationary

• High attraction to mobile, high attraction to stationary

• Low attraction to mobile, low attraction to stationary

• Low attraction to mobile, high attraction to stationary

What portion of the paper chromatography system works to slow down molecules under investigation?

• Mobile phase

• Stationary phase

• solvent

• paper