How do pH papers work?

Alitmus paperics are the most versatile kind, as they measure pH over the widest range from 0 to 14. They are among the most popular indicator papers, precisely because of their large range, yet relative accuracy of measurement.

Phenolphthalein papers are already limited to a pH range of 8.3-10, but are more accurate.

But do you know how indicator papers work properly?

In the case of Alitmus papers, the use is quite simple: dip the paper into the solution to be tested for one second and then place it on a non-absorbent pad. Within a few seconds, the paper becomes coloured, and you can use the colour scale on the packaging to determine the approximate pH (the most acidic pH is determined by a deep red colour, which goes through yellow, green and blue to an alkaline pH).

In the case of phenolphthalein papers, the procedure is identical, but the pH is determined based on a different coloration. The slips are white and if the pH of the solution exceeds 8.3, the slip will turn red.

The phenolphthalein papers are already limited to a pH range of 8.3-10, but are more accurate.

The different colouring is caused by the reaction of the solution to the substance used in the papers (litmus or phenolphthalein), so the colour range does not apply to all indicator papers and you should always check which type of paper you are using to measure pH

You can also read much more extensive information on the topic of pH measurement in the blog post Measuring the pH of a product.

The article was prepared for you by

Martina Oboňová

Please write to us at marketing@handymade.sk with any of your comments and suggestions .

How do pH papers work?

Many of you will be familiar with pH indicator papers.

But do you know how indicator papers work properly?