02.03: Methyl Red

Here’s another chemical that had me scratching my head when I picked it. How on earth can I come up with an entire video about a pH indicator? Well, as it turns out, I found quite a few things to do with it. And I learned more than I expected I might!

The first experiment I found was the one about pH not crossing over the phase boundary. The paper had a nice photo of five test tubes ranging from red to yellow, and each one had an upper organic layer that was roughly the same shade of orange. I didn’t feel like making buffer solutions like they did, so I figured I’d just titrate the color with some dilute hydrochloric acid and sodium hydroxide. Well, that didn’t work to the same effect, but it got me to think and learn why that might have happened.

The rest of the experiments I found were to do with destroying methyl red for pollution control purposes. There were a number of different methods, and one in particular that I wanted to try. Unfortunately, the one I really wanted to try requires a piece of equipment that was cost-prohibitive. The equipment needed was a mercury vapor lamp. I found the bulb at a local hardware store, but there was nothing to plug it into. A little further research suggests that UV-radiation might be effective in place of the mercury lamp, but I was already done filming by then.

I was happy that, despite the horrible sound quality of the finished product, I had learned from ferroin what makes for the best oxidizing environment. Methyl red is decolorized on an industrial scale with something called “Chloramine-T” through oxidation of the dye. So I used the strongest oxidizer I have, according to ferroin. I did get a result, but not nearly as clean as the powdered decolorizing carbon.

Finally, my delay in cleaning up taught me that methyl red solutions are inherently unstable. Aged solutions are still functional as pH indicators, but there is a problem with the formation of solid gunk. I’m not going to keep a solution prepared and waiting for use on the shelf anymore. I was planning on packing up some methyl red solution for sale, but now I’m reconsidering how to do that and not waste the product.

Next up, we’re getting toxic!

-Jason