Draw a labelled diagram of the apparatus used to filter the mixture and collect the sodium chloride solution - Edexcel - GCSE Chemistry - Question 5 - 2020 - Paper 1

To obtain pure sodium chloride crystals from the filtrate, you can follow these steps:

1. Heat the solution: Gently heat the sodium chloride solution to evaporate some of the water, concentrating the solution.
2. Leave to crystallize: After concentrating, allow the solution to cool or sit undisturbed at room temperature, encouraging crystal formation.
3. Scrape the crystals: Once crystals have formed, scrape them from the container or pat them dry using filter papers. Alternatively, you could filter the crystals and decant the liquid to remove excess solution. Finally, allow the crystals to dry completely.

The Rf value is calculated using the formula: $Rf = \frac{distance\;moved\;by\;the\;dye}{distance\;moved\;by\;the\;solvent}$ In this case, the solvent front moved 6.5 cm. If the dye moved 0.6 cm, then the Rf value would be: $Rf = \frac{0.6}{6.5} = 0.0923$ Alternatively, if the dye moved 3.9 cm, the Rf value would be: $Rf = \frac{3.9}{6.5} = 0.6$

To improve the accuracy of the Rf value, you could use a longer piece of filter paper or different paper. This adjustment would allow for more separation of the dyes as they travel and could result in a clearer measurement of distances.

To separate the dyes in ink sample Y, consider using a different solvent that can effectively dissolve the ink. Using a solvent that interacts better with the ink components may facilitate better movement along the chromatography paper, enabling clear separation of the dyes.