Colourful Chemistry Or Not

I have been reading about how colour vision deficiency (colour blindness) can cause issues for people. I was very interested in this article ( and several others about the difficulties in reading certain graphics and maps when red-blue colour scales are used. For example, temperature anomaly charts are often red-white-blue with red being hotter than average and blue being colder than average. Some forms of colour vision deficiency will stop a reader accurately differentiating these scales. I think the chart and map making disciplines may be ahead of chemistry in thinking about this – most of the articles I can find relate to earth and environmental sciences.

Colour blindness is about 7% prevalent in males and 0.4% in females and it differs in severity and type. 7% probably means that at least one student in a class has an issue with ‘seeing’ colour and this may cause problems. Many people are not aware that they are colour blind. Possible issues for chemistry teaching may be:

  • litmus paper/pH paper/universal indicator

  • red-blue shading on graphics (molecular orbital diagrams, where colours are used for emphasis, charts etc)

  • transition metal chemistry where observing colour changes and noting down those observations are key (and often assessed)

If students are working in pairs, the lab partner may be able to help out with some tasks.  But what if the task in question is part of a practical exam?  Generally I have avoided things that require too much recording of colour for practical exams, and where recording colour changes would be appropriate in the observations, it’s only been worth a tiny quantity of marks. In terms of other teaching we can ensure that our diagrams and graphics are created using appropriate colour schemes where we have the option – we don’t have a choice if they are textbook graphics. I’ve been moving towards purple-orange, have never used red-blue as it’s always felt a little jingoistic (hah!).

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