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Difference Between Carbonate and Bicarbonate

Last updated date: 07th Dec 2023
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What is Carbonate and Bicarbonate: Introduction

To differentiate between carbonate and bicarbonate:Chemistry encompasses a vast array of compounds, each with its own distinctive properties and applications. Among these compounds, carbonates and bicarbonates hold particular significance. This comprehensive guide aims to explore the dissimilarities between carbonates and bicarbonates, providing an in-depth analysis of their composition, properties, and applications.While they share some similarities, there are key difference between carbonate and bicarbonate.Understanding characteristics of carbonate and bicarbonate is a big part of chemistry, and it's especially important for students studying for tests like NEET and JEE. In this article, we'll look at some of the most important ways in which the characteristics of carbonate and bicarbonate are the same and different.


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What is Carbonate?

Carbonate refers to a chemical compound composed of a carbonate ion (CO32-) combined with a metal or hydrogen ion. It is an anion, carrying a negative charge. Common examples of carbonates include calcium carbonate (CaCO₃), sodium carbonate (Na2CO3), and magnesium carbonate (MgCO3). Carbonates exist in various forms such as solids, powders, or crystals.

Properties of Carbonates:

  • Solubility: Carbonates generally exhibit low solubility in water, with exceptions like sodium carbonate and potassium carbonate, which are highly soluble.

  • Reactivity: Carbonates react with acids to form carbon dioxide gas (CO2), water (H2O), and a salt. This reaction is known as neutralization.

  • pH Level: Carbonates have a high pH, making them alkaline in nature. They can act as buffers to maintain pH stability in certain solutions.

  • Decomposition: Upon heating, carbonates decompose to produce carbon dioxide gas and an oxide of the metal they contain.

Carbonates find numerous applications across various industries. Calcium carbonate, for example, is used in the production of cement, as an antacid in medicine, and as a filler in the manufacturing of paper and plastics. Sodium carbonate, also known as soda ash, has applications in glass production, water treatment, and as a cleaning agent. Additionally, magnesium carbonate is utilized in the manufacturing of fireproof materials, as an antacid, and as a drying agent in the food industry.

What is Bicarbonate?

Bicarbonate, also referred to as hydrogen carbonate, is a chemical compound composed of a bicarbonate ion (HCO3) combined with a metal or hydrogen ion. Bicarbonates are typically formed when carbon dioxide (CO2) dissolves in water. Sodium bicarbonate (NaHCO3) and potassium bicarbonate (KHCO3) are commonly encountered bicarbonates.

Properties of Bicarbonates:

  • Solubility: Bicarbonates are highly soluble in water, making them suitable for various applications.

  • pH Level: Bicarbonates are amphoteric, meaning they can act as both acids and bases depending on the solution they are present in. They can help regulate pH levels in biological systems.

  • Buffering Capacity: Bicarbonates possess excellent buffering capacity, enabling them to resist pH changes caused by the addition of an acid or base.

  • Decomposition: Upon heating, bicarbonates decompose to form carbon dioxide, water, and the corresponding carbonate.

The applications of bicarbonates are diverse and significant. Sodium bicarbonate, commonly known as baking soda, is utilized as a leavening agent in baking, as an antacid, and as a cleaning agent due to its abrasive properties. Potassium bicarbonate is employed as a fire extinguishing agent, in the production of effervescent tablets, and as a pH regulator in the food industry. Bicarbonates also play a crucial role in physiological processes within the human body, serving as a buffering system to maintain blood pH levels.

Differentiate Between Carbonate and Bicarbonate







Contains the carbonate ion (CO32-)

Contains the bicarbonate ion (HCO3-)


Charge on Ion





Trigonal planar molecular geometry

Tetrahedral molecular geometry


Solubility in Water

Generally insoluble in water except for alkali metals

Highly soluble in water


Acid-Base Behavior

Reacts with strong acids to produce carbon dioxide

Acts as both weak acids and weak bases



Calcium carbonate (CaCO3), Sodium carbonate (Na2CO3) Magnesium carbonate (MgCO3)

Sodium bicarbonate (NaHCO3), Potassium bicarbonate (KHCO3), Ammonium bicarbonate (NH4HCO3)


Common Uses

Manufacturing of glass, cement, ceramics Neutralization of acids, antacids, dietary supplements

Leavening agent in baking, fire extinguishers, pH regulation in swimming pools


In Class 12 Chemistry, understanding the differences between carbonates and bicarbonates is crucial for comprehending various chemical reactions and their applications. Carbonates, with a -2 charge, are generally insoluble in water and react with strong acids to produce carbon dioxide. On the other hand, bicarbonates, with a -1 charge, are highly soluble and exhibit both acidic and basic properties. They play important roles in baking, fire extinguishing, and pH regulation. By recognizing the unique characteristics of carbonates and bicarbonates, students can gain a deeper understanding of these compounds and their significance in chemistry and real-world applications.

FAQs on Difference Between Carbonate and Bicarbonate

1. How do carbonates and bicarbonates behave in acid-base reactions?

Carbonates react with strong acids, such as hydrochloric acid, to produce carbon dioxide, water, and the corresponding salt. This reaction is known as an acid-base reaction. Bicarbonates, on the other hand, can act as both weak acids and weak bases. In the presence of an acid, they act as a base and accept a proton, converting into carbonic acid. In the presence of a strong base, they act as an acid and donate a proton, forming carbonate ions.

2. Differentiate between carbonates and bicarbonates on the basis of their solubility in water.

The solubility of carbonates and bicarbonates in water is a key distinguishing factor between the two compounds. Carbonates, in general, are insoluble in water, except for carbonates of alkali metals such as sodium, potassium, and lithium. When most carbonates come into contact with water, they do not readily dissolve and instead form a precipitate. This limited solubility is evident in minerals like calcium carbonate found in limestone or seashells, which exhibit low solubility in water. On the other hand, bicarbonates display high solubility in water. When bicarbonates, such as sodium bicarbonate or potassium bicarbonate, are introduced to water, they readily dissolve, resulting in the formation of a clear and alkaline solution.

3. How do carbonates and bicarbonates affect pH?

Carbonates and bicarbonates can affect pH due to their ability to act as weak acids and bases. Bicarbonates, in particular, are important in regulating pH. When bicarbonates dissolve in water, they release bicarbonate ions (HCO3-), which can act as a buffer and help maintain the pH balance in various systems.

4. Can the solubility of carbonates and bicarbonates be affected by factors other than water?

Yes, the solubility of carbonates and bicarbonates can be influenced by factors other than water. One important factor is the presence of other ions in the solution, which can affect the equilibrium between the solid carbonate or bicarbonate and their dissolved ions.

For example, the presence of certain metal cations, such as calcium (Ca2+) or magnesium (Mg2+), can decrease the solubility of carbonates through the formation of insoluble precipitates. This phenomenon is commonly observed in hard water, where the high concentration of calcium and magnesium ions can lead to the formation of scales or deposits in pipes and appliances.

Similarly, bicarbonates can be influenced by the presence of other ions. In the presence of strong acids, bicarbonates readily release carbon dioxide gas and convert into carbonates, which are less soluble than bicarbonates. This acid-base reaction results in a decrease in the solubility of bicarbonates and the formation of carbonates.

Temperature can also affect the solubility of carbonates and bicarbonates. In general, an increase in temperature tends to increase the solubility of both carbonates and bicarbonates, although the effect can vary depending on the specific compound.

5. How does the solubility of carbonates and bicarbonates affect carbon dioxide levels in the atmosphere?

The solubility of carbonates and bicarbonates affects carbon dioxide levels in the atmosphere. When carbonates react with acids, they release carbon dioxide gas, contributing to atmospheric CO2 levels. Bicarbonates can act as a reservoir for dissolved carbon dioxide and release it under certain conditions, such as low pH or carbonate ion concentration. This solubility-driven release of CO2 from bicarbonates influences the exchange of carbon dioxide between the atmosphere, bodies of water, and marine organisms, impacting the global carbon cycle.