making up Universal indicator

[Ocker]

I go through UI by the bucket load, so when making, I use ten times dye in ethanol and store as I want more just mix 4 solutions and add 2:1 Distilled water real quick and quantities are much more accurate!
Mushroom, who told them it was home made, just lie, look them straight in the eye, and ask ,What did you do wrong?
Attack is the best defence!

[Robb]

Hi All,

If you find yourself with the same problem, simply add dilute HCl until you can drive the Universal Indicator back to the green colouration.

This will not affect the solution in anyway when it is needed.

Cheers,

Robb.....

[dime]

Hi Ocker
Maybe I'm a little fuzzy as it is Friday after all. Could you please run your method by me again, not necessarily in kinder language, but perhaps with commas or something as I can't quite picture what you are doing, and it sounds interesting.

[Ocker]

By ten times, I mean make 4 stock bottles of
0.25g of Thymol Blue in 1L of Ethanol
0.63g of methyl redin 1L of ethanol
5g of Phenolphthalein in 1L of ethanol
2.5g of Bromthymol Blue in 1L of ethanol
When I need more UI I take 10ml of each add 200ml of ethanol and make up to 1L with Distilled water and buffer till green
this is more accurate as I don't have balance to measure 0.0625g

[RosalieM]

I'm glad I don't have to make my own universal indicator, but if I did I reckon I'd be stealing your idea Ocker!

[kimmy]

By making the stock bottles up makes it all look alot easier as I seem to be making Universal Indicator up many many times each year - will try it this way - thanks.

KIMMY

[MHourigan]

Hi JustSue, am just checking out what is happening, and has anyone else noticed that the times given on these recent posts are out of wack? Someone check it out seems like I'm in a time warp!!

[RosalieM]

They seem to all be in the right order for me!

[Ocker]

Some of us are still on daylight saving time

[The Search Engine]

Can I ask a blonde question?
I just made up some phenolpthalein indicator today and the mixture got warm when I added the distilled water. I was just following "The Laboratory" and there was no info on what would happen. Is this supposed to happen?
One bewildered, L plater Labby.

Cheers,
Patti

[Lyn]

This is a blonde answer. Yes.
Unfortunately this blonde can't give you the definitive reason why. Perhaps it is because all those ethanol molecules are so busy trying to fill the vacant spaces between the water molecules that the energy they give off is heat energy.
Try this: Add 50ml of methylated spirits to 50 ml of water and see if you end up with a 100 ml of liquid.
Lyn.

[The Search Engine]

Ahh - thanks, Lyn. Vacant spaces... LOL

Patti

[Narelle01]

I was going to have a go at making my own UI but i don't have Thymol blue :(
is there a sub i can use???

Or is there a chem i can 'water' my current UI down with to make it go just a bit further ?

[matchstick]

its only 1st term..surely the science faculty has enough money in their annual budget to
buy some already made

[fibreweb]

I have just made up my 4th litre of Universal indicator for this year.
We could not afford to buy it already made up.

[Narelle01]

we are buying 2 bottles of it - but we have been thru gosh knows how much - so i thought I might as well make it up to see how i go - we have bottles of the chems - so why not...

I have tracked down some thymol...so going to get mixing on thursday.
Is it easy?

[franco]

I have tracked down some thymol...so going to get mixing on thursday.

I'm sure you're aware Narelle, but for those who are inexperienced, thymol and thymol blue are two totally different chemicals and it's the latter that is used in the preparation of UI.

Regards,
Fran

[Narelle01]

yes sorry - my bad...thymol blue....