Universal Indicator

Hi, I have been asked to set up 14 test tubes with all the universal color's in. I have never done this before so any advice appreciate!

Many thanks
Alli
 
Buffer solutions are the way to go as Emma R says. You can spend hour trying to get it right with acids and alkalis.
 
Dyes and buffer solution would be my suggestion. I found the colours changed quite quickly as they absorbed bits from the air, plus it is a pain to do.

This, food colouring is your best bet. Also add a pinch of lead nitrate to prevent mould growth, seal them with rubber bungs and keep them aside somewhere. Not only can they serve as a decorative feature, but they last ages. The flasks I made have been like this for years now. I am aware the colours are not exactly like universal indicators (they're more saturated), but what the heck.
 

Attachments

  • thumbnail_20211203_095124.jpg
    thumbnail_20211203_095124.jpg
    170.4 KB · Views: 34
Yeah, that sounds like a huge pain. I'd suggest that they do Rainbow Fizz instead, that way they can see the entire colour gradient accurately without you having to futz around with 14 buffer solutions.
 
I realise this is late but I found this searching for something else.
We have just done red, orange, green, blue and purple using dilute HCL, dilute NaOH and a pH meter. all classes doing topic at same time so weve stored them in 250ml bottles to put in test tubes when needed. It's been a success so far
 
Top