Hello, I have a query regarding Universal Indicator.

We use full range UI with a pH 7 = yellow. We have recently noticed some catalogues are selling two types of full range UI with pH 7 = Yellow or Green. We are thinking pH7 should be green, this indicator is more expensive than the one we have been buying, is it worth the additional expense and why are there two colours for pH 7? What are peoples thoughts on this matter?

Paul Murphy

We only buy UI from one supplier as it gives the traditional colour range. They are one of this site's sponsors based in Hyde near Manchester. Sorry to be criptic but I don't know if I can name them on here.
I would think it depends on the syllabus as well, if the students need to know green = 7 then I would go fro the green, if not then yellow should be fine.
I use a full range with Green as 7
There are a few different recipes of "universal indicator". Some are cheaper and/or easier to make than others. You make your choice and you pay your money.