States of matter and changes of state：練習問題

A student performs a paper chromatography experiment to identify components in a green food dye.
The stationary phase in this process is the:

The table below shows the results of a paper chromatography experiment for four different inks (A, B, C, D) using a polar solvent.

Ink A: Two spots, distances 2cm and 5cm
Ink B: One spot, distance 4cm
Ink C: Two spots, distances 2cm and 6cm
Ink D: One spot, distance 5cm

If the solvent front traveled 8.0 cm, which statement is correct?

A student has a mixture containing a liquid hydrocarbon and an insoluble solid impurity. Which sequence of experimental techniques should the student use to obtain a pure sample of the liquid and then determine if it is chemically pure?

In paper chromatography, a student uses a solvent to separate a mixture of three dyes. Dye A has an \(R_f\) value of 0.20, Dye B has an \(R_f\) value of 0.50, and Dye C has an \(R_f\) value of 0.85.

Which of the following is a correct deduction about the affinity of these dyes?

The following table shows the melting and boiling points of four substances. Which substance is a liquid at \(50^{\circ}\text{C}\)?

Substance A: MP \(-100^{\circ}\text{C}\), BP \(-35^{\circ}\text{C}\)
Substance B: MP \(15^{\circ}\text{C}\), BP \(120^{\circ}\text{C}\)
Substance C: MP \(80^{\circ}\text{C}\), BP \(250^{\circ}\text{C}\)
Substance D: MP \(-5^{\circ}\text{C}\), BP \(45^{\circ}\text{C}\)

Explain, in terms of particles, what happens to the energy of a substance during the process of condensation.

A student separates a mixture of three dyes using paper chromatography. The \(R_f\) values are calculated as 0.25, 0.40, and 0.75.
If the solvent front moved 12.0 cm from the baseline, calculate the distance moved by the most soluble dye and explain how the stationary phase affects its movement.

A student separates a mixture of three soluble substances using paper chromatography. If substance X has a very high affinity for the mobile phase and a low affinity for the stationary phase, describe and explain its final position on the chromatogram relative to the solvent front.