Neutral solutions do not cause a change of color, although there are some brands of blue Litmus paper that will turn purple if the substance is neutral.
p H strips change color when they come in contact with a solution.
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The p H scale measures how likely a substance is to give up protons (or H ions) and how likely that substance is to accept protons.
The color must be compared with a chart to get a number and determine if the liquid is acidic, basic or neutral.
For example, if you are testing a citrus juice, the color change would happen around the 1 or 2 p H level (acidic) whereas water would change color around 7 (neutral).p H strips are considered to be more sensitive than Litmus paper because Litmus paper cannot give quantitative results.The choice of which method is appropriate depends on the requirements or sensitivity needed for the test.The word "litmus" comes from the old Norse word for to "dye" or "color." To perform the test, place a drop of liquid sample on a small strip of paper or dip a piece of litmus paper in a small specimen of the sample.Ideally, you don't dip litmus paper in an entire container of a chemical; the dye could contaminate a potentially valuable sample.The litmus test is a quick method of determining whether a liquid or gaseous solution is acidic or basic (alkaline.) The test can be performed using litmus paper or an aqueous solution containing litmus dye. The blue paper changes to red, indicating acidity somewhere between the p H range of 4.5 to 8.3.(Note, however, that 8.3 is alkaline.) Red litmus paper can indicate alkalinity with a change to blue.Red paper that does not change color indicates the sample is an acid.Blue paper that does not change color indicates the sample is a base.Chemicals and solutions are often classified as being acidic, basic or neutral.These properties are determined by the p H scale, which ranges from 0 to 14.