Interpreting Chromotography

• What is the result of chromatography analysis called?

  Chromatogram
• What does the Rf value represent in chromatography?

  It is the ratio of the distance travelled by the solute to the distance travelled by the solvent.
• How do you calculate the Rf value using the formula?

  Rf = $\frac{\text{distance travelled by solute}}{\text{distance travelled by solvent}}$
• How do you find the distance travelled by the solute on a chromatogram?

  Measure from the baseline to the center of the spot.
• What does it indicate if the Rf values of a pure sample and an unknown mixture match?

  The substances may be the same, but it doesn't definitively prove they are.
• What are standard reference materials (SRMs) used for in chromatography?

  To check the identities of components in a mixture.
• How does chromatography help in purity testing?

  A pure substance will move as one blob, while a mixture can produce multiple blobs.
• What is gas chromatography (GC) used for?

  To analyze unknown substances.
• What must happen to substances before they can be analyzed by gas chromatography?

  If they are not gases, they must be vaporized.
• What is the mobile phase in gas chromatography?

  An unreactive gas, such as nitrogen.
• What is the stationary phase in gas chromatography?

  A viscous liquid, such as oil, coated on the inside of the tube.
• What happens to the unknown mixture in gas chromatography?

  It moves along the tube with the mobile phase until it exits the other end.
• What is the term for the time it takes a chemical to travel through the tube in gas chromatography?

  Retention time
• How is retention time used in gas chromatography?

  It is used to identify the chemical.
• What does each peak on the gas chromatogram represent?

  Each peak represents a different chemical.
• What does the x-axis on a gas chromatogram represent?

  The retention time of the chemicals.
• What do the relative areas under the peaks on a gas chromatogram indicate?

  They show the relative amounts of each chemical in the sample.
• What does a sample of a pure substance produce on a gas chromatogram?

  A single peak.