[Chemistry Class Notes] on Citric Acid Pdf for Exam

Citric acid is a strong organic compound with the chemical formula HOC(CH₂CO₂H)₂. It is always known as a colorless weak type of organic acid found. It is generally present naturally in citrus fruits. In this biochemistry, it is known as the intermediate cause involved in the citric acid cycle, which occurs or is found in the metabolism of all aerobic organisms. 

Citric acid is available in natural form in several fruits and vegetables. Still, most notably, you can taste their presence in citrus fruits like lemons and lime that contain a high volume of citric acid. It might take you by surprise, but Citric acid can take up to 8% of the fruit’s total dry weight.

 

Discovery of Citric Acid

The first isolation of Citric acid took place in 1784 by the chemist named Carl Wilhelm Scheele, who experimented by crystallizing it from lemon juice. Citric acid is present in two forms in nature. One is the water free form, which is called anhydrous, and the other one is monohydrate. However, in both forms, the chemical name, and the Citric acid structure remains the same. 

 

On the other hand, Citric acid’s isolation on an industrial scale first took place in 1890 in Italy. As the citrus fruit company used hydrated lime, which is Calcium hydroxide, to precipitate Calcium citrate in the juice. The Calcium Citrate was being isolated and got converted back to acid, which then gets diluted by sulfuric acid. 

 

 

Citric Acid Chemical Formula

Citric acid is said to be a tribasic acid. As a result, if you want to prepare acidic salts of Citric acid, you can do it by carefully balancing pH before the compound’s crystallization starts to occur. One of the examples of acidic salts derived from this acid is Sodium citrate. 

 

The Citric acid chemical formula is C6H8O7. In its naturally occurring form, the Citric acid crystals have white colour, which you can also find on the top of sour candies. 

Preparation of Citric Acid

You can get Citric acid from the market as it is a weak acid. You do not need to have a special order to buy it from a local chemical store. If you want to prepare it by yourself, you need to follow the given steps.

 

Step 1:- First, you need to have lemons, and we mean lots of lemons. You need 450 ml of lemon juice to extract a good amount of crystallized Citric acid. Test the lemon juice by using a pH strip. The result should be around a 2 or 3 pH scale. 

 

Step 2:- Add a little bit of eyedrop, which contains 10% strength Sodium hydroxide, and test the solution again. Now take the coffee filter and pour down the solution into another glass. Also, at this stage, check for any solid particles in the solution that you poured into a new flask.

 

Step 3:- Now put 28 grams of Calcium Chloride into 70 ml of distilled water and combine both the solutions in one glass and heat it. 

 

Step 4:- Again, filter out the solution using a coffee filter to get calcium citrate out of it. Now, as the Calcium citrate is taken out, mix it with heavily diluted sulfuric acid, and then stir it. Filter out the solution with water, and store the citric acid in a beaker. 

 

Step 5:- Heat the solution on medium heat so the water gets evaporated from the beaker. Finally, filter out the Citric acid and let it cool down in a bowl. 

 

Properties of Citric Acid

We have already discussed the structure of Citric Acid. Now, let us move to citric acid’s properties. The citric acid common name is citrate, and the systematic IUPAC name of Citric acid is 2-Hydroxypropane-1,2,3-tricarboxylic acid. 

 

The Citric acid density is 1.66 g/cm³. The density is one of the important properties of any chemical compound as it defines how much of it can mix in any particular substance. The molecular weight of Citric acid, which is present in the monohydrate form, is 210.14 g/mol. 

 

Uses of Citric Acids in Daily Life 

• There are several ways in which Citric Acid benefits humankind. Below are some of the major uses.

• First, in beverages, Citric acid provides tartness and enhances the fruits and berries flavours. Also, with its addition, the antimicrobial preservatives get a boost, and it provides adjustments in pH to give uniform acidity to the soft drinks. 

• In frozen fruits, Citric acid makes pH go lower to make oxidative enzymes inactive. 

• In pharmaceuticals, this acid works as an effervescent combined with bicarbonates to provide rapid dissolution of active ingredients.

Importance of Chemistry

Chemistry is really important and efficient for the research and study of living organisms because it helps students and scientists to understand the life processes of every living thing on earth at the molecular level. At any molecular level, every process of life takes place due to the involvement of various minor or major chemical reactions.

How to Study Chemistry?

Thus, the students need to learn their chapters well and understand all the chemistry concepts by practicing with a maximum number of past years’ question papers and sample question papers available on the website. This will help them to understand the time management skill and learn the marking schemes that carry maximum marks and plan which question needs what type of answers. Break down larger portions into smaller effective points and write them down in a separate notebook so it will help you in revising before the exams. 

Make note of the important questions that keep repeating in the recent past year question papers and give more weightage to those questions and prepare a little extra because it might repeat in the current year also. If you have any doubts about the equations and chemical formulations that are taught during the classes then try to spend some extra time in the lab and get to understand all the concepts by trying out the experiments and practicing them really well. This will definitely help you write your formulas and equations really well.