Practise mixtures questions by classifying formulae or diagrams, choosing separation methods and using chromatogram distances or spots.
This question is about gases.
The table gives information about five gases.
Use information from the table to answer these questions.
Each gas may be used once, more than once or not at all.
Give the name of the gas that is a compound.
Give a reason why it is not possible to give information for air in the table.
A student has two solids, X and Y .
One of these solids is a pure substance and the other is a mixture.
Describe how the student could identify which solid is pure and which is a mixture by measuring a physical property of each solid.
This question is about apparatus used in the laboratory.
The diagram shows apparatus used to obtain pure water from sodium chloride solution by simple distillation.
Explain why it is necessary for water to flow continuously in and out of the apparatus.
A student uses paper chromatography to investigate the dyes in five different inks, V, W, X, Y and Z.
This is what she uses.
- a beaker
- a piece of chromatography paper with a pencil line drawn near the bottom of the paper
- a solvent
- inks V, W, X, Y and Z
The chromatogram shows the results for inks V, W, X, Y and Z.
Explain which ink contains a dye that is insoluble in the solvent.
Explain which two inks contain the dye that is likely to be the most soluble in the solvent.
Explain which two inks may contain only one dye.
Describe how the student should set up and carry out her experiment.
You may draw a diagram to help with your answer.
Explain why the line on the paper is drawn in pencil rather than in ink.
A student uses paper chromatography to investigate the dyes in five different inks, V, W, X, Y and Z.
This is what she uses.
- a beaker
- a piece of chromatography paper with a pencil line drawn near the bottom of the paper
- a solvent
- inks V, W, X, Y and Z
One dye in ink Y moves 4.3 cm when the solvent front moves 6.5 cm.
Calculate the Rf value for this dye.
Give your answer to 2 significant figures.
Rf value = ................................