Blue litmus paper is a fast easy way to test for acidity; simply dip a strip into the solution in question and if it is acidic, it will turn red immediately; only $1.75.
You can make wider/longer strips using the 200x250mm-8x10" blue litmus paper sheets which can also be used for water leak detection.
If you need more than a simple qualitative (yes or no) answer that a liquid is acidic or alkaline, we supply universal pH indicator paper sheets that are 8x10" (200x250mm).
Use pH4-5-10 test strips if you are measuring weak acids or bases since litmus paper is not very accurate between pH5.5-8.5.
The pH litmus indicator chemical, 7-hydroxyphenoxazone, seen the image below, is extracted from lichens. It can be added to water or filter paper to make test strips. It changes from blue to red in the presence of acids such as lemon or orange juice, vinegar, urine or milk. You can even build a physical model of 7-hydroxyphenoxazone using our 3D molecular model builder.
The image shows the blue litmus papers as they are available in both vial & pad; the strips are identical and turn from blue to red when dipped in an acid solution.
Test Strip Documentation
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