The waste water processing plant on a remote space station is contaminated with heavy metal pollutants, known as metal ions. Scientists onboard the station need to identify the contaminants in order to remove them from the water supply. Paper chromatography can be used to identify these metal contaminants in the waste water. A drop of waste water solution is placed on the chromatography paper while the bottom of the paper is set in a solvent that travels up the paper as shown on the right.
The solvent carries the metal ions up the paper. Some ions move faster, and therefore higher than others, resulting in a separation as they move up the paper. The paper is dried, then stained, causing the ions to appear as coloured spots.
Each spot is then identified by comparing the distance it has travelled with the distance the solvent has travelled using the mathematical expression given on the right. This is known as the Rf value of the ion.
The table on the right shows Rf values for 5 ions.
Table 1
The table on the right shows Rf values from 3 samples of wastewater. The same solvent was used for all ions and samples.
Table 2
1) The information in Tables 1 and 2 supports the conclusion that Sample 3 contains:
2) Based on the information in Tables 1 and 2, we can conclude that sample 2 contains:
3) Based on the information in Table 1, which of the following lists the metal ions in order from the fastest to slowest speed with which they moved up the paper?
4) Consider the information in Table 2. Which of the following chromatograms shown on the right best illustrates the chromatogram of sample 1?
5) In order to identify a metal ion using paper chromatography, one should know the:
6) A metal ion known as "X" was identified as having an Rf value of 0.78 and appears red when stained. A chromatogram was analysed of a sample of water and a red spot was found 3.8 cm from the start. The solvent travelled 4.87 cm from the start. Is "X" present in the water?
Explain.
7) The speed of a metal ion depends on
8) A sample of water was analysed using paper chromatography. Before the chromatogram was stained to reveal the colour of the ion a grey spot was noticed 7.2 cm from the start. Which one of the following metal ions is it likely to be?
