Magnesium Carbonate

Definition

Magnesium carbonate, as the name suggests, is a carbonate having positively charged Magnesium ion and negatively charged carbonate ion. It is an inorganic salt. 

Before reading about Magnesium carbonates in detail, it is necessary that you know what is a salt or carbonate in chemistry. In chemistry, salt is a compound that is made up of the combination of a positively charged compound and a negatively charged compound. In other words, salt is a compound made up of anion and cation. However, the overall charge of the salt is zero - it is neutral since salts must have an equal number of anions and cations. Inorganic salt is different from organic salts. It does not have any C-H bonds. Carbonate is that compound that is made up of Carbon and Oxygen. Its Chemical formula is CO₃²⁻.

Magnesium Carbonate: In Detail

So now that you know the background, let us talk about MgCO₃ in detail. As said, MgCO₃ is a salt. Why is it a ‘salt?’ – This is because the compound is made up of MG²⁺ and CO₃²⁻, the two ions negate each other because of the equal amount of positive and negative charge. 

MgCO₃ is mostly obtained by mining Magnesite. Magnesite is a form of MgCO₃. Magnesite is a mineral that occurs as white or grey crystalline solid. Magnesite is the altered form of Magnesium-rich rocks. The miners do not need to drill too much deep inside the earth to mine Magnesite. As a result, Magnesite is easy to mine. Magnesite is processed to synthesize magnesium carbonate. 

The salt can also be found in the form of dihydrate mineral known as barringtonite. Found first in Barrington Tops, Australia, this dihydrate mineral is formed from the leaching of basalt. There is also the trihydrate form of MgCO₃ known as the nesquehonite which is quite similar to barringtonite. Another hydrated form of magnesium carbonate is lansfordite. This one was first found in Lansford. And it is a pentahydrate. As you can guess from the names, the dihydrate has 2 moles of H₂O along with MgCO₃, the trihydrate form has 3 moles and the pentahydrate form of magnesium carbonate has 5 moles of H₂O.

The above minerals are all natural sources of magnesium carbonate; but what about the industrial manufacturing of MgCO₃? Yes, it is also possible. In the laboratory, the reaction between any (water-soluble) magnesium salt and sodium bicarbonate will result in the production of MgCO₃.

Properties of Magnesium Carbonate

The key properties of magnesium carbonate are:

  • Magnesium carbonate can either appear as bulky white powder if it is heavy or as light white powder if it is light.

  • MgCO₃ is odourless but as the Chemical Book website points out - because of its high absorption capacity, it can absorb many types of odour.

  • MgCO₃ cannot dissolve in water or alcohol but it can dissolve in inorganic acids.

Group 2 Metal Carbonates

If you look at Group 2 in the periodic table, you will find six metals. All these metals are known for their thermal decomposition properties. It means that the carbonates of the metals of this group will undergo thermal decomposition and spit out their corresponding metal oxides and CO₂.

This is also true for the carbonate of magnesium. When magnesium carbonate is heated, it dissociates into MgO and CO₂.

MgCO₃ → MgO + CO₂

Again, similar to other group 2 metals, magnesium carbonate gives out CO₂ and H₂O when it reacts with acids like sulphuric acid and hydrochloric acid.

Here goes the summary of the properties of magnesiun carbonate:

Summary of Magnesium Carbonate Properties

Properties of Magnesium Carbonate 

Heavy MgCO₃ appears as grainy powder while light MgCO₃ appears as a light thin powder.

Although magnesium carbonate is odourless, due to its high absorption power, it can absorb odours from other sources.

MgCO₃ is insoluble in water or alcohol but it can dissolve in inorganic acids

Just like the other Group 2 metal carbonates, MgCO₃ breaks into MgO and Carbon dioxide when heated.

Just like the other Group 2 metals, magnesium carbonate releases CO₂ and H₂O when reacted with acids.

The molecular weight of magnesium carbonate in its anhydrous form is 84.3139 g/mol.

The molecular weight of heavy, hydrated form of MgCO₃ is 383.32

The molecular weight of light, a hydrated form of MgCO₃ is 365.30. 

The decomposition temperature of MgCO₃ is 350-degree Celsius.


Uses of Magnesium Carbonate 

The top applications of magnesium carbonate are as follows: 

  • The main usage of MgCO₃ is the production of Magnesium Oxide. Magnesium oxide is used in the medical field to mitigate heartburn and acid reflux. It aids the digestive system. It is also used as a mild laxative.

  • Because of its insulating properties, MgCO₃ is used as fireproofing.

  • Because of its absorption properties and pH balancing power, it is used in the cosmetic industry.

  • Because of being an antacid, it is also used in toothpastes to get rid of acid formation in the mouth.

  • It is used to stiffen ink without ruining its colour.

  • MgCO₃ is also used in the filtration process.

Magnesium Carbonate in the Medical Industry 

Today the general public is aware of magnesium carbonate because of its medicinal properties. People who have low amounts of magnesium in the blood, take the magnesium carbonate pills. Magnesium carbonate is extremely useful when it comes to the removal of acid from the stomach. It is highly effective in treating acidity, heartburn and indigestion. However, with all its usefulness, MgCO₃ is not devoid of harmful effects. Consumption of too much magnesium carbonate can result in addiction.

Therefore, to recap what we have learnt so far:

  • MgCO₃ is a carbonate or salt having Magnesium cation and negatively charged carbonate ion. It is naturally found in the form of minerals like Magnesite or dolomite.

  • The Mg in magnesium is positively charged and the CO₃ is negatively charged. The two ions make the compound neutral as a whole.

  • In the lab, MgCO₃ can be obtained with the reaction between any magnesium salt that is soluble and sodium bicarbonate.

  • Magnesium carbonate can either appear as granular white powder if it is heavy or as light white powder if it is light.

  • It is an odourless compound but can absorb odours from other sources.

  • The molecular weight of magnesium carbonate in its anhydrous form is 84.3139 g/mol.

  • MgCO₃ starts decomposing at 350-degree celsius.

  • MgCO₃ is primarily used to obtain magnesium oxide.

  • MgCO₃ is used to make antacids.

  • It has insulating properties. That is why it is used in fireproofing.

  • MgCO₃ is also used in the water industry as a filtrating agent.

Magnesium Carbonate is an extremely useful mineral or carbonate that has medicinal properties. The great thing about MgCO₃ is it is not that hard to mine. There are very few naturally occurring compounds that are so useful and so at the same time so easy to obtain. This is the speciality of the compound magnesium carbonate.

FAQ (Frequently Asked Questions)

1. What is Magnesium Carbonate?

Ans. MgCO3 is a carbonate or salt having Magnesium and CO3. The Mg is positively charged while the CO3 is negatively charged. It is naturally found in the form of minerals like Magnesite or dolomite.

2. Why is Magnesium Carbonate Known as a Salt?

Ans. In chemistry, salt is a compound that is made up of anion and cation. However, the overall charge of the salt is negated because of the equal intensity of the positive and negative charge.  Inorganic salt is different from organic salts. It does not have any C-H bonds. MgCO3 fits the description. Hence it is called salt.

3. What are the Properties of Magnesium Carbonate?

Ans. The properties of MgCO3 are -

  • It is white.

  • It is odourless.

  • MgCO3 is insoluble in water or alcohol but it can dissolve in inorganic acids

  • The molecular weight of magnesium carbonate is 84.3139 g/mol. ( Without H2O)

  • If you heat MgCO3 it will give out MgO and CO2.

  • When treated with acids, it gives out CO2 and H2O.

  • It has the same properties as the other Group 2 metal carbonates.

4. What are the Uses of MgCO3?

Ans. The main applications of MgCO3 are:

  • MgCO3 is primarily used in the production of Magnesium Oxide.

  • MgCO3 has insulating properties. Hence it is used as fireproofing.

  • MgCO3 has great absorption power. That is why it is used in the cosmetic industry.

  • Because of being an antacid, it is also used in toothpaste to get rid of acid formation in the mouth.

  • It is used to stiffen ink without ruining its colour.

  • MgCO3 is also used to filter water.

  • MgCO3 is used to treat acidity and heartburn.