Hey all
Just as a quick question. A few weeks ao I had some trouble finding phenolphaline (i think this is correst spelling) for titration and I came accross phenol red. This product is used for testing ph levels in pools. Now can this product be used for titration or not? I am only asking as it is alot easier to find. On the net they are different, but I thought I would ask the question anyway.
cheers all

Try turmeric, you can eat it and it's cheap and works really well so they say

Phenol red changes at a different pH range to Phenolphthalein. You really want an indicator that will change somewhat above 7, because you are titrating a weak acid with a strong base.

pH range of Phenolphthalein is ~8.2-9.8, phenol red is around 6.8-8.3.

I have read, that curcumin (the chemical in tumeric that works as an indicator) has an indicating range of 7.4-8.6. So your results may be slightly different with a tumeric indicator (in comparison to Phenolphthalein - depending on how well you use it).

I've not used a tumeric indicator before, but lots of people seem to use it with success.

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in my experiments with phenol red vs phenolphalene i achived the same reading from the same oil source in the same conditions. i now solely use phenol red for availability and cost compared to phonolphalene.
Hope this helps.
Cheers Nick.

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Cheers
Nick.

Roidio 2001 Holden Rodeo 4x4 2.8L TD. 2.5" Straight through exhaust sytem, heat exchanger shower system. 2" Body Lift,
And lots of fruit, B100 for 25,000 no problems.

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Thanks for all your input. I just thought of posting the question as I have a friend that can get me Phenolphtaline (FREE), but they had a baby and were off work. This is why I posted the question. Now, atleast I know if I have trouble I can try phenol red as a substitute. however, I might do an experiment just to try it as there are 2 conflicting replys here.
Thanks again all

I've always used Phenol Red without problems, but am about to try tumeric as my latest bottle of phenol red is running out and I have stacks of tumeric.

In comparison testing I have performed

If you push Phenol red and Turmeric to their darkest colour you will achieve virtually identical numbers to phenolphthalein

This makes a lot of sense (provided you don't go too far) since this would occur at about pH 8.3 for phenol red, and pH 8.6 for tumeric, which corresponds roughly with the first colour change of phenolphthalein at pH 8.2.

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Thanks all. My friend works in a lab and usually gets me phenolphtaline, but she had a baby and wans't at work. Murphy law, I ran out of the stuff when she was off so I used tumeric, but I came accros phenol red everywhere and thought I would post a question as it is really easy to come by. Well now I know if Ihave trouble again I have 2 alternatives. I posted the question as I too was a little hesitant to use tumeric, but it seems to work ok. Anyway thanks to all who replied, much appreciated.

Perhaps do some tests when you have access to phenolphthalein again, on what colour change is observed from phenol red and tumeric, using the titre value (the amount of base you added) as determined from using phenolphthalein.

That way if you do have to use one of your alternatives at some point in the future, you have an idea on what colour change to aim for.

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