Science Buddies: "Ask an Expert"

Why should pH test strips be wet prior to testing an unknown liquid? A reference would be very helpful as well. Thanks!

Frio310 - I'm not sure I agree that a pH test strip has to be wet (neutral pH of 7 liquid). I think you are fine using a dry test strip in your test. Maybe someone else can elaborate on your concern.

Rick MAra

It is not necessarily a concern of mine. A question was posed for an assignment of mine, as to whether or not we agree with wetting the strip prior to use, why or why not? There was a note in our text saying if you have an acid or a base wihtout a water element, the results are meaningless, hence the use of water to pre wet the strip. Looking for opinions and hopefulyl a references, I have scoured the internet and cannot coem up with anything

Well, yes, if you are measuring the pH of a dry substance, you're not going to get much of a measurement on a dry test strip. They are designed to work on solutions. That said, I wouldn't think that this would be a very accurate way to get a measurement. It would seem to be better to produce a solution of some known molarity using your dry material, and then using the strip on that solution.