Interpreting chromatograms | Exit Quiz | Oak National Academy

The pattern that forms as a result of chromatography is called a ...

Answer explanation

The pattern that forms as a result of chromatography is called a chromatogram.

Match the keyword to its description.

• solvent front

• the furthest distance the solvent travels along the stationary phase

• sample line

• a ratio of the distance a component of a sample travels vs the solvent

• Rf value

• where the sample is placed on the stationary phase

Answer explanation

The sample line is where you place the sample on the stationary phase. The Rf value is the ratio between the distance a component of a sample travels and the distance the solvent travels. The solvent front is the furthest distance the solvent travels

Which of the following pieces of apparatus and equipment is not essential for chromatography?

• chromatography paper

• container (e.g. beaker)

• pencil

• ruler

• a pen

Answer explanation

Chromatography paper, a container (like a beaker), pencil, and ruler are all integral to performing chromatography. A pen, while useful for taking notes, is not needed for chromatography as you should use a pencil to draw the sample line.

How can chromatograms be used to identify if a sample is a mixture?

• by the colour of the sample line

• by the presence of multiple spots

• by the number of peaks

• by the Rf value of a spot

Answer explanation

A mixture is indicated by multiple spots, while a pure substance would show a single spot.

A vertical analysis of a sample’s chromatogram can visually determine if a sample is pure or a mixture. This is known as ___ analysis.

Answer explanation

A vertical analysis of a sample’s chromatogram can visually determine if a sample is pure or a mixture. This is known as qualitative analysis.

Given a solvent front at 7.0 cm and a substance spot at 2.3 cm on a chromatogram, calculate the Rf value.

Answer explanation

2.3 ÷ 7.0 = 0.328571 Your answer should be quoted to an appropriate number of significant figures (s.f.), and as both the values in the question are to 2 s.f. the answer should be 0.33.