[Chemistry Class Notes] Lactic Acid Pdf for Exam

Lactic acid, also known as lactate, is a chemical byproduct of anaerobic respiration. It refers to a process where cells produce energy without having oxygen around. Lactic acid gets produced in yoghurt by some bacteria. It is also present in your gut and blood. Your muscles and red blood cells often deposit the lactate into your blood. So, lactic acid is an organic one. It’s a chiral molecule, and it has two optical isomers, which are L-lactic acid and D-lactic acid. The presence of a carboxyl group adjacent to the hydroxyl group makes lactic acid an alpha-hydroxy acid. In this article, you can learn about lactic acid structure, its definition, uses, and sources.    

What is Lactic Acid?

Lactic acid is one of the organic acids. The chemical formula of the lactic acid is C3H6O3. It has two optical isomers, Levo and Dextro, making itself a chiral molecule. L-isomers are commonly present among living organisms. The lactic acid has a significant part in various biochemical processes. It gets produced by the muscles during intense activity. 

Lactic acid is soluble in water. It looks white in its solid-state and becomes colourless in the liquid state. Milk acid is another name of lactic acid. When lactose or milk sugar undergoes fermentation, the lactic acid gets produced. You can also find it in other dairy products like cottage cheese, yoghurt, etc. 

Just so you know, a Swedish chemist, named Carl Wilhelm Scheele, isolated the lactic acid from milk for the first time in 1780. Also, the soluble salt of lactic acid, such as calcium lactate can act as a source of calcium. The PH of 1 mM of lactic acid is nearly 3.51. You can learn more about lactic acid as below. 

Structure of Lactic Acid

Below you can find the structural representation of lactic acid or C3H6O3.  

(Images to be added soon)

The extended formula of lactic acid is CH3CH(OH)CO2H, and it has a molar mass of 90.08 g/mol. Since a single carbon houses hydroxyl group (-OH) and carboxylic group (-COOH), the molecule gets classified as alpha-hydroxy acid. The central carbon is a chiral as it appears and the other two substituent groups are a hydrogen atom on a methyl group (-CH3). It results in two different structures: L-lactic acid (+) and D-lactic acid (-).

Properties of Lactic Acid

• Lactic acid is colorless or yellow syrupy, during its liquid state. In solid form, you can find it in the white powder. 

• The molecular weight or molar mass of lactic acid is 90.08 g/mol. And it’s PH level is 3.51 per 1 mM of lactic acid.

• The melting point of lactic acid is 530 Celsius, and the boiling point is 1220 Celsius. It is soluble in water and ethanol. 

• Lactic acid is corrosive to any metals and tissue. Thus, overuse and overconsumption of the lactic acid can come with severe side effects. 

Uses of Lactic Acid

There are numerous lactic acid uses, and the first thing to note is that your body can produce lactic acid on its own. But, there is a significant requirement for industrially produced lactic acid. It can get formed using a synthetic process or fermentation. The latter involves usage of nutrients like amino acids, vitamins, peptides, glucose, and salt. These nutrients get combined with microbes, which further uses nutrients to give out lactic acid. 

Once the lactic acid is ready, it can be used for various purposes as below. 

• Personal products and healthcare products

• Food preservatives

• Dairy products, like yoghurt

• Cleaning, laundry, and dishwashing products

• Paint and coating additives

• Furniture care products

• Textile dyeing and leather tanning

• Pharmaceuticals  

Applications of Acids and Basic Substances

Due to the different properties of acids and bases, they have a significant role in real-life applications. Some of the applications are- 

Applications of Acid Substances

• Citric acid is a key ingredient in lemons and oranges. Acids can also be utilized to preserve food.

• Sulfuric acid is widely used in car batteries, which are commonly used to start the engines of automobiles.

• Acids are used in the industrial production of explosives, dyes, and fertilizers.

• Phosphoric acid is one of the key ingredients in many soft drinks.

• Vinegar is a diluted form of acetic acid and it features several home applications like preserving food, etc.

Applications of Basic Substances

• Ammonium hydroxide is one of the most important reagents used in laboratories.

• Any extra acidity in the ground (soil), could be neutralized by utilizing slaked lime.

• Ca(OH)₂ (also known as slaked lime or calcium hydroxide) is used to make dust which is used for bleaching powder.

• Calcium Hydroxide is used to make dry mixes which are utilized in design or artwork.

• The production of soap and paper requires the utilization of salt (sodium hydroxide).

• NaOH is utilized in the making of rayon.

• Magnesium hydroxide(also referred to as milk of magnesia) is usually used as a laxative and it also decreases any extra acidity in a human’s stomach. This property qualifies it to be an antacid.