PH paper

November 1, 2021

PH paper is a measurement tool that allows you to identify how high the concentration of hydrogen ions is in solutions. It is a practical and disposable material, because unlike other types of instruments, once used it cannot be used again.

Due to the importance when determining the PH of different substances in the chemical field, it is common to find it in laboratories, you can also find it as litmus paper.

What is PH Paper?

It is a paper designed to measure the PH of substances, keeping in mind that the PH refers to the level of acidity or alkalinity. Each solution is found at a point on said scale that is marked with colors, whose graduation normally ranges from 1 to 14. With 1 being the most acidic and 14 being the most alkaline, indicated in colors from red for acid to blue. In the middle of the scale are the neutral solutions.

The PH paper is impregnated with indicators, in such a way that they react with substances indicating a color, depending on their pH level. The acronym “PH” itself indicates hydrogen potential. The papers being impregnated with indicators, undergo a process of protonation or deprotonation, when being in contact with the solutions.

So the PH paper is a paper with several colors that contain indicators and measure the concentration of hydrogen ions in solutions, to determine their level of acidity or alkalinity. The most common indicators are methyl orange and phenolphthalein, although there are many others such as methylene blue, bromophenol blue, silver nitrate, and more.

What is PH Paper for?

The PH paper fulfills the function of determining if a solution is acidic, neutral or alkaline . There are other types of PH meters such as the PH-meter, an electrochemical sensor used when it is required to have an exact precision of the PH levels of a solution.

Thanks to the PH paper it is very easy to determine the concentration level of hydrogen ions in a solution.

Uses of PH Paper

PH meters are used in more sectors than you probably imagine, and it is that keeping the PH of solutions controlled is not a matter merely of the research field. One of the areas where it is most used is food ; Used to determine the acidity in the production of wine, even in common foods such as cheese.

In the maintenance of swimming pools, the use of PH paper is also applied, since being in constant contact with various chemicals they must be kept at optimal levels so as not to affect their users. The agricultural field is another area that uses this instrument, because something essential in this sector is to check the acidity of the soils and this is one method of doing it.

How does PH Paper work?

I already mentioned that the PH value scale is made from 0 to 14 but now I will proceed to explain a few things so that you can apply the role in the correct way. The main thing you should know is that you can only measure the PH of aqueous solutions, that is, that contain water, oils cannot be measured.

It is important that you also be clear that although the scale goes from 0 to 14 , there may be solutions that exceed this, acids that have a negative value and alkaline that exceed the limit of 14. However, it is not common to find these substances and They are not measured with PH paper but rather with a PH-meter.

To measure the PH of a solution you must have your aqueous solution and immerse the paper strip in it, wait a few seconds, from 10 to 15 with the submerged strip so that it is well impregnated with the substance and then remove it. Then you wait for the color change and compare it with the scale. The PH paper packages come with samples of the colors with their corresponding value.

If you want to determine the PH of a gas, I must tell you that the procedure is a bit different, since the paper only measures the PH in aqueous solutions, you have to let the paper soak in distilled water and then expose it to the gas so that dissolves in water. If the paper does not change color it is because its value is neutral.

Remember that red, orange and yellow tones indicate acidity, green is neutral and blue tones are alkaline; It is a scale from red to blue; 0 to 14, where 0 to 6 is acid, 7 is neutral, and 8 to 14 is base or alkaline.

PH Paper Types

PH paper is also called litmus paper, but they are the same. The different types of PH paper are in any case red and blue . The blue litmus paper is technically the origin of the current one, when it comes into contact with an acidic substance it turns red.

Its counterpart, red litmus paper, takes on this color after adding sulfuric acid to the blue mixture (which contains potassium carbonate and ammonia) and turns blue after coming into contact with an alkaline solution. Both papers are reusable after drying , a very remarkable feature.

Characteristics of PH paper

PH papers come in commercial presentations in the form of strips or even rolls; They bring a guide with various colors, the scale that you can refer to to classify the type of substance once you have done the test.

Although there are different sizes, these are not really large, in general their distribution has been standardized so they do not present significant changes.

Importance of PH paper

Currently there are considerable advances in PH measurement technology and with the PH-meter, most of the cases are solved in the area of ​​chemical, pharmaceutical research and other disciplines that require great precision. However, this does not mean that the PH role has been left behind.

If there is this kind of specialized meter, why is PH paper still being used? Basically because this is a practical, inexpensive and really useful tool. Even if it does not give an exact diagnosis, the approximation is accurate enough to be a reliable result; making it the appropriate option in most cases.

PH is an extremely important measure that is found in all kinds of substances that surround you and is even linked to alterations in health, if the appropriate measurements and precautions are not taken.

Dr. Loony Davis5
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Born and raised in Brussels in an English family, I have always lived in a multicultural environment. After several work experiences in marketing and communication, I came to Smart Water Magazine, which I describe as the most exciting challenge of my career.
I am a person with great restlessness and curiosity to learn, discover what I do not know, as well as reinvent myself daily, someone who is curious about life and wants to know. I enjoy sharing knowledge.
This is my personal project but I also collaborate in other blogs, it is the case, the most important web on water currently exists in the US, if you are interested you can read my articles here.

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