Macherey-Nagel qualitative indicator paper for the crossing of pH 8.3, in 2 presentations covering different measuring ranges.
90712
90713
A qualitative indicator paper that shows the crossing of pH 8.3, where phenolphthalein turns from colourless to pink. It gives a yes or a no, not a value.
Phenolphthalein has one very sharp transition, and a great deal of routine chemistry is built around exactly that point: it is the endpoint of an alkalinity titration and the marker used to check whether concrete has carbonated.
A qualitative paper does one thing and does it without ambiguity. There is no scale to interpolate and no lighting to argue about: the colour changes or it does not.
That makes it the right tool when the decision is binary — proceed or do not — and the wrong tool when anyone needs to know how far past the threshold the sample is. For a value, use an indicator paper with a scale or a meter.
The pink fades in air as carbon dioxide is absorbed; read it at once and do not judge a strip left on the bench.
Supplied in 2 presentations covering different measuring ranges.