Yorkshire Philosophical Society

Event Information

Colourful Chemistry

Dr Annie Hodgson, Department of Chemistry, University of York

How have chemists brought colour to our lives? Why do chemists use colour to help them understand the world around us? What makes fireworks look so brilliant? Discover the answers to these and other burning questions in this exciting lecture, delivered by Dr Annie Hodgson from the University of York. Prepare to be amazed as colours change before your eyes and find out why Colourful Chemistry makes Father Christmas feel extra jolly!

Join us for this Christmas Family Event on campus and bring your friends to this large new lecture theatre:

NEW VENUE!   Lecture Theatre, Spring Lane Building, University of York, Campus West YO10 5DS

The building is located at the edge of Spring Wood, between Derwent College and the Berrick Saul building.

On the University map D3 D32

Member’s report

Chemistry has brought colour to our lives in the many ways Chemists use colour.  Compare the early images of Father Christmas in a dingy brown coat with the development of new dyes giving us the bright red coat of our contemporary figure. The first demonstration showed us how a bath duck can change colour as the temperature is raised in the water.  Colourless leuco dyes are added to other coloured forms of crystal violet lactone to enable the process.  Then we saw how dyes added to a universal indicator can change from purple to blue to orange to yellow and then to white. This process also indicates how acid or alkali the solution is from the most acid PH1 to the most alkali PH14. Annie also demonstrated the iodine clock reaction: measuring the rates of reaction with changes of concentration of starch and iodine to change to blue/black. Chemists’ experiments can bring advantages with new products such as the UV bracelet you wear which changes colour when UF light is sensed to remind you to use sunscreen or seek shelter.

Thinking about the colour in firework displays such as New Year’s Eve in Sydney harbour led to a demonstration of the addition of different metal salts.  For example, calcium added gives red colours; potassium – lilac; copper – green and sodium – yellow.  Snowflake type fireworks include burning magnesium metal salts as used in flash photography.  The most spectacular demonstration was the Fireflies with ammonia and oxygen in a large flask and when chrome oxide (III) is heated to give a green powder added to the flask this gives a shower of fireflies’ reaction.  To conclude the evening volunteers with individual glow sticks moved them in unison to give a mini light show.

Catherine Brophy