Could someone tell me if Ph pens are a reliable source to determine acidity? Thank you.
Just to avoid confusion, you’re talking about small, electronic pH meters like the ones on this page, right?
If so, then, yes, I’ve found them to be accurate and reliable. Just make sure you calibrate regularly and replace the batteries when necessary.
I’ve certainly found portable pH meters to be easier to read than the colorimetric methods I’ve used. I used to spend spend minutes looking at a sample and wondering, “Is that closer to the aqua, the blue-green, or maybe the blue?” Now I get an unambiguous number within a few seconds
I am actually talking about a pH pen, that looks like a marker, used to test paper for acidic content.
However, those big, honkin meters look cool and I bet a piece of paper would respond in an instant.
Actually, those meters can only be used to test the pH of a solution.
To measure the pH of paper, I belive there are “hot-extraction” and “cold-extraction” procedures that can be used to produce solutions that can be measured with a normal, glass-electrode pH meter. After a little Googling, I’ve found standards published by ASTM and ISO on how to do this.
This page has an annotated bibliography on methods of measuring the pH of paper that may be of interest: http://palimpsest.stanford.edu/byorg/abbey/ap/ap04/ap04-1/ap04-107.html. It looks fairly old, though, so I’m not sure what’s considered “state-of-the-art” these days.
Your Googling looks good. I thought I did Googling, but it must have been done differently. I think I just wrote pH pens. I should have explored differently. Who knows what I wrote. :rolleyes:
These site look really good. I will explore them this evening. I check marked all of them. Thank you.