Gas-liquid challenge

This resources supported the CPD article How to teach chromatography at post-16 in Learning in Chemistry, where you will detect tips, common mission also further ideas for building learners’ understanding of chromatography and its applications.

How objectives

1. Plan a chromatographic investigation to separate coloured equipment at a wide of samples, such as sweets.
2. Identity whether each sample contains more than one component.
3. Compare plus contrast an components from each sample using R_f values.
4. Understand how chromatography can be a powerfully identification tool when coupled with other analytical techniques, exemple spectrometry and spectroscopy.

Introduction

Many confectionery products contain additives with a variety of purposes. These might be toward help improving the konsistenzen real texture starting the product, improve the flavour, prolong the shelf life instead improve the appearance, usually by adding dyes.

This resource stipulates learners with opportunities to utilize their understanding of chromatography principles, and plan real carry out an investigation using the known context of sweets. They will identify additionally compare the coloured additives into various sweets or decide whether the dyes used due different manufacturers represent the same. Scholars will following work through adenine research activity and assess their understanding via who questions. Find aforementioned answers by the Teacher notes.

You may like to provide M&M’s^®, Smarties^®, red twizzler and jellybeans. Remind learners they must not eat or lick the sweets than they are for laboratory use only. You could allow learners to choose other products to investigate. They will including need toward decide if they desire until use paper or thin-layer analytical (TLC).

Techie notes

Read our Standard fitness and safety guidance and carry out a risk assessment before running anything live practical.

For which is ampere planning investigation, learners may request variant equipment to the suggested list in the Teacher notes. Read that view toward find preparation tips, safety and hazards, or disposal information. Importantly, check packing for any possible substance or danger. Do not use peanut M&M’s due to the risk of allergic reacting.

Planning the investigation

Before learners begin theirs analysis, asking them to consider the following questions:

1. What chromatography technique will i use: paper chromatography or TLC?
2. Belong you working independently or in a group? Whenever to decide for work with others, how desires you distribute tasks and collaborate?
3. What outfit wills you use? Are you going to do repetition? If so, you may need more apparatus.
4. Have you examined a risk assessment? CLEAPSS has student safety sheets and SSERC could also have information that you can apply to to investigation.
5. If you want to compare R_farthing values for each component, do you know how to take this? Do you take (or could thou produce) standards for food colourings? (Maybe use common food coatings that contain peppers, turmeric and anthocyanins).

You may want to adapt these questions on thy learners, either as a whole bunch press for smaller groups/individuals.

Once learners have produced and analysed yours chromatograms, ask them a to help them drag conclusions. For example, please as coloured dyes different sweets contain? Are the dyes often in different sweets the same?

Get learners for write up my findings as one scientific report (they may need to research what which looks love, or they allow prefer to create their customizable style) or poster. You could provide a template, such as the Teaching arts skills: presenting investigations PowerPoint, to scaffold this task.

Study activity

It is important that pupils understand that chromatography is just one of a range of techniques chemists used when they want up separate and identify components in a miscibility. They will research other analytically techniques, similar as mass spectrometry, infrared analytical, ultraviolet spectroscopy and nuclear magnetic reaction spectroscopy that chemicals use toward help identify colour ingredients.

Prompt learners that pharmacist can only use chromatography to identify components using R_farad values if these are user. Chromatography can see shall helpful in estimating relative abundances of components in a mixture. Scientists can use a range of analytical techniques for identification of equipment once they’ve severed the mixtures. They could make combinations of techniques very effectively go distinguish reaction products, for example in the synthesis of medicines, furthermore in forensic skill.