Determination of pH of Some Solution Experiment

Dhristi JEE 2022-24

What is pH Determination?


Before understanding, what pH determination is? It is essential to understand what is the meaning of pH. The full form of pH is the potential of hydrogen. It is a quantitative scale that is used to determine or measure the acidity or the basicity of any liquid solution.


For instance, in the case of pure water, the concentration of hydrogen ion is 10 - 7 gram-equivalents per litre, which is considered to be neutral as it falls in the pH 7 category. We say a liquid concentration is acidic if the pH level is less than seven and we say, the liquid concentration is basic or alkaline if the pH is more than 7. This is how the pH of a given solution is determined.


How to Determine the pH Through an Experiment?

There are several experiments through which the pH of a certain liquid concentration is determined; one such is given below.


The theory rests on the fact that each chemical has an inclination towards being a base, or an acid or being neutral. When an acidic liquid is dissolved in the water, it releases free hydrogen ions (H+ ions), whereas, when a base is dissolved in the water it produces hydroxyl ions (OH- ions). The strength or weakness of the acidic solution or basic solution depends on the release of H+ ions or OH- ions when it is dissociated.


Measurement of pH

pH was invented by a Danish chemist named Soren Peder Lauritz Sorensen. The value of the pH will be low if the concentration of the hydrogen atoms is high. pH is defined as the negative logarithm (base 10) of hydrogen ion concentration.


  • Liquid concentration, whose level is lower than seven on the pH scale, is said to be acidic.

  • Liquid concentration, whose level is higher than seven on the pH scale, is said to be basic.

  • Liquid concentration, whose level is equal to 7 on the pH scale is neutral.


pH Determination Methods

There are several methods of pH determination.


pH Paper:

Special strips of paper are made by submerging them in the chemical compound and then drying it. When this paper is dipped on a liquid substance, it changes colour. The change of colour is then compared to the colour chart to determine the actual pH level or in which category that certain liquid belongs.


pH Meter:

there is a device known as the pH meter, which is used to determine the pH level of a substance. This electronic device has a special electronic bulb that is sensitive to hydrogen ions. The ones that are present in the solution. The bulb produces a signal which is then amplified by and is shown in a meter format in the electronic meter attached. The meter displays the pH level and in which category does the substance belong. For very precise measurement, the pH meter should be calibrated before each measurement.

The pH of Fruit Juices

People who are obsessed with the idea of dieting are quite taken by the pH levels of different fruit juices. A study has shown that juices which are lower than pH level 4 or belong to the category of pH 4 can be extremely damaging to the teeth as well as the person's health. For this purpose, the pH of fruit juices is mentioned below:


  • Lemon Juice - 2.25

  • Very Fine Grapefruit Juice - 3.22

  • Minute Maid Cranberry Grape - 2.71

  • Ocean Spray Strawberry Kiwi Juice Cocktail - 2.90

  • Ocean Spray Cranberry - 2. 56

  • Minute Maid Natural Energy Pomegranate Berry - 3.33

  • Ocean Spray Cran-Grape - 2.79

  • Minute Maid Orange Juice - 3.82

  • Minute Maid Cranberry-Apple Raspberry - 2.79


Study of pH of Some Fruit Juices Project Determination of pH of Acid Solutions

There is an easy way to determine the pH level or the acidic level of a given solution.


Aim

Using pH paper and a universal indicator, determine the pH of solutions such as fruit juices containing various acids, bases, and salts.


Apparatus

  • Test tubes

  • Universal indicator

  • pH paper

  • White tile

  • Dropper

  • Some juices


Procedure

Pour the liquid into separate test tubes. Take the white tile and place the strip of paper on it. Take the help of the dropper to extract the liquid which you want to test and put it on the strip of pH paper. As soon as the liquid solution gets in touch with the pH paper, it will start changing colour. Now, match the colour to the universal chart that has been given to you to know if the solution is alkaline or neutral or acidic.


In the case of Cranberry juice, it will be acidic. Cranberry juice falls directly under the category of acidity because its measurement on the pH scale is typically between 2.3 to 2.5. Foods or juices which are above pH level 7 are considered to be basic or alkaline.


Similarly, limes, lemons, and tangerines - all of which are rich in ascorbic acid - feature a pH of 2.4, 3.1, and 4.1, respectively.


Precautions to be Taken During the Experiment

  • Make a careful match between the colour of the solution and the standard colour pH chart.

  • Keep the pH strips out of the reach of any chemical fumes.

  • Maintain the pH paper clean.


Conclusion

pH determination helps people to understand if the given solution is acidic, basic or neutral, which, in turn, helps them to determine which liquids are safe or easy to consume. The way of measuring the pH scale is extremely easy, either that person can use pH paper or pH meter.

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FAQs (Frequently Asked Questions)

1. Which Liquids can be Consumed by Humans?

The liquids or the solutions or juices that can be consumed by humans are the ones that have a higher pH level. Juices that are lower than 4 in the pH scales should be avoided as the acidic concentration on those are more and can have a damaging effect on the teeth.

2. How can a Person Know That the Given Solution is Acidic or Basic or Neutral?

As discussed above, the substances or liquids which fall in the category below seven is considered to be acidic. The ones who fall in the category beyond the seven marks are considered to be basic, and the ones who fall exactly on seven are considered to be neutral.

3. Define Acids, Bases and pH indicators?

Acids are chemicals that, when dissolved in water, produce free hydrogen ions (H+ ions). Hydroxyl ions are formed when bases are dissolved in water (OH- ions). Hydrogen ions are abundant in acidic solutions and scarce in basic solutions. A universal indication is a pH indicator made up of several chemical compounds.

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