Several months a go I purchased an Acid Test "kit". A few months
ago I purchased another Acid Test "kit" from a different retailer.
The first one had Sodium Hydroxide solution of N/10 and the
Phenolphthalein was 1%. The 2nd kit had Sodium Hydroxide solution of
1/5N and the Phenolphthalein appears to also be 1%.

The calculation needed to arrive at the acid percent is different
between the two kits ... I assume due primarily to double strength of
the Sodium Hydroxide solution in the 2nd kit.

I have run out of the Sodium Hydroxide solution in both kits but I
still have lots of the Phenolphthalein solution. I'd like to order
just the chemicals rather than the "kits" due to lower price and
larger quantities. It looks like the Phenolphthalein solutions are the
same.

My question is can I continue to use the Phenolphthalein solution that
I still have regardless of the Sodium Hydroxide solution strength that
I order? Do these chemicals have a shelf life (or do they keep for at
least a few years)?

Thanks again for your feedback.

Roger L. Pelletier , Aurora, NE USA