Bicarbonates

Bicarbonates refer to the intermediate form in the deprotonation of carbonic acid. Class 12 students should learn about bicarbonates as a whole, while also understanding the various types of bicarbonates that exist in the world.

The bicarbonate formula is HCO3-, which represents a polyatomic anion. In this chapter, you will learn about the chemical and physical properties of such compounds, along with their various applications. We would also establish a relationship between carbonic acid and bicarbonate anion. The chapter also focuses specifically on certain bicarbonates, including potassium, calcium and sodium.

Structural Relationship Between Bicarbonate Anion and Carbonic Acid

Bicarbonates are not only an important chemical compound but also essential for proper respiration. Acid-base composition is regulated and maintained, using the respiratory system’s ability to excrete extra carbon dioxide. Additionally, the kidneys have the ability to remove excess waste in the urine. This process is known as the buffering system of bicarbonates.

If bicarbonates are present abundantly, expelling acidic waste from the human body becomes immensely difficult. Thus, bicarbonates act as antioxidants in the body, ensuring better health. 

The bicarbonates buffering systems contain weak acid, such as carbonic acid (H2CO3) and weak bases, known as bicarbonates (HCO3).

H2CO3 + H2O ↔ H+ + HCO3–

Here the first compound is carbonic acid, while the resulting substances include an H+ ion and the bicarbonate anion.

Applications of Bicarbonates

Different bicarbonates have various uses. Therefore, one needs to study about specific types of bicarbonates to learn about their diverse applications. Still, here are some of the common applications of bicarbonates that you need to consider – 

• Sodium bicarbonate acts as a leavening agent for baking.

• In some cases, bicarbonate can alleviate discomfort caused due to the excessive acidity in the digestive juices.

Apart from Calcium bicarbonate, potassium bicarbonate and sodium bicarbonate are two of the most important products belonging to this group. Hence, we will focus on these two compounds in this chapter to help students form a basic idea regarding bicarbonates. 

Sodium Bicarbonate

Also known as, bicarbonate of soda, sodium bicarbonate is a chemical compound with the formula NaHCO3. A French chemist, named Nicholas Leblanc was the first person to produce sodium carbonate under laboratory conditions in 1791. However, it was in 1846 that two reputed New York bakers started mass-producing sodium bicarbonate in the form of baking soda.   

Even today, this compound is almost indispensable for bakers around the globe, acting as one of the finest leavening agents for the production of various kinds of breads. Refer to this table listed below to acquire a better understanding of this compound’s properties.

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Refer to the figure above to understand the structure of a sodium bicarbonate molecule. Basically, it features a bicarbonate anion and a sodium cation. You can notice an ionic bond between the oxygen atom with a negative charge and the sodium ion holding a positive charge.

Applications of Sodium Bicarbonate

Bicarbonate soda is primarily found in various elements of cooking. However, this compound has several other useful applications as well. Listed below are some of its uses – 

1. This bicarbonate compound is highly efficient when it comes to killing cockroaches and other pestilence. Additionally, application of the same can prevent fungal growth. 

2. Application of sodium bicarbonate can prevent body odour, especially in your armpits. It also combats irritation across these places of the body.

3. The compound can disinfect surfaces, making it useful in clinics and hospitals for cleaning surgical and other medical equipment.

4. Due to the compound’s antibacterial properties, many people use it to clean kitchen equipment as well. Doing so limits the chances of bacterial contamination in food items.

5. Individuals undergoing chemotherapy are often injected with sodium bicarbonate to reduce side effects from this cancer treatment. 

6. Dentists use such bicarbonates to clean mouth and teeth.

7. Its usage in cooking and baking is the perhaps the most popular application of sodium bicarbonates. If you are looking to bake bread, you need to incorporate this compound into the dough. This bicarbonate acts as a leavening agent, ensuring soft and spongy breads every time.

Potassium Bicarbonate

Potassium bicarbonate is another highly useful bicarbonate compound, with a chemical formula of KHCO3. It is a monopotassium salt of H2CO3. Similar to sodium carbonate, the potassium bicarbonate exhibits alkaline properties. In most instances, this compound is used as an antacid, which can reduce discomfort caused by stomach acids.       

Some of the bicarbonate’s properties are listed in the table below. You should learn as many of these physical properties as possible.

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Refer to the figure above to assess the molecular structure of a potassium bicarbonate molecule. As we know, bicarbonate formation is only possible after deprotonation of carbonic acid. From the figure, you can see that a central carbon atom connects with three oxygen atoms. One of these oxygen atoms further forms a bond with a hydrogen atom. Due to the effect of resonance, the -1 charge is quickly delocalised through the other oxygen atoms.

Producing Potassium Bicarbonate

Deriving potassium bicarbonate is simple. All you need is a solution of potassium carbonate and water. Treat this solution with carbon dioxide for the formation of such bicarbonates. Here is the chemical reaction – 

CO2 + K2CO3 + H2O → 2KHCO3

Quick Question

Q. What would be the resulting components when potassium carbonate undergoes decomposition at temperatures of 120 degree Celsius?

Ans. After decomposition, potassium bicarbonate breaks down into its individual components. Therefore, you can expect the formation of potassium carbonate, water and carbon dioxide molecules to form once the decomposition process is complete.

Additional Physical Properties

Listed below are few additional physical properties that potassium bicarbonate exhibits – 

• This compound is completely odourless.

• Its solubility in water is 22.4g per 100 ml at a temperature of 20 degree Celsius.

• This compound’s acidity is equal to 10.329.

Applications of Potassium Bicarbonate

Such a compound has a diverse range of applications, which include the following – 

• It can act as leavening agent in baking, effectively liberating carbon dioxide from the bread dough.

• Due to its non-toxic and inexpensive nature, this compound is often used to regulate pH.

• This bicarbonate is an important component in almost all chemical fire extinguishers, especially the dry ones.

• In medications, the same compound can act as a buffering agent. In essence, this is another way in which it regulates pH in drugs.

• Can reduce acidity in soils, thereby promoting better agriculture in certain soils.

• The same can be used as a taste enhancer in club sodas.

Another important usage for this substance is in organic farming, where it can control mildew growth.

If you are having difficulty in this chapter, know that you are not the only one struggling to get through the bicarbonates chapter. Consequently, at Vedantu, we provide experienced teachers, who conduct classes online.

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