Magnesium Hydroxide Formula

What is the Chemical Formula of Magnesium Hydroxide?

Magnesium hydroxide is an inorganic chemical compound that is present as a white solid. As already known a hydroxide is any polyatomic anion made up of oxygen and hydrogen having a chemical formula (OH)\[^{-}\] which clearly shows that it is an anion with one negative charge. It is well known that magnesium atoms are capable of donating two electrons to form a cation, in order to achieve a stable electronic configuration. Hence, a cation of magnesium and a polyatomic anion of a hydroxide combine with each other to form a neutral salt compound with the magnesium hydroxide formula. Thus, the chemical formula of magnesium hydroxide is given as Mg(OH)\[_{2}\]. It is also commonly known as milk of magnesia and hence the given formula of magnesium hydroxide is also the formula for milk of magnesia. 


Common Properties of Magnesium Hydroxide

The mineral of magnesium hydroxide that is naturally available is known as brucite. It naturally occurs in the form of 1:2:1 clay minerals in chlorite, in which it takes place in the interlayer position. The salt of magnesium hydroxide has the physical form of a white crystalline solid mineral. 


The structural formula magnesium hydroxide has is given below showing the arrangement of the ions involved as per the chemical formula of magnesium hydroxide :

[Image will be Uploaded Soon]

Some of the common physical properties of magnesium hydroxide are described below:

  • The molar mass of magnesium hydroxide as calculated from the magnesium hydroxide chemical formula is 58.3197 g/mol.

  • The chemical compound having the chemical formula for magnesium hydroxide is an odourless inorganic compound. 

  • The density of magnesium hydroxide is 2.344 g/cm\[^{3}\]. 

  • The melting point of magnesium hydroxide is 350\[^{0}\]C and it decomposes completely on boiling.

  • Interestingly, the compound represented by the magnesium hydroxide chemical formula has very low solubility in water. 

  • The crystal structure of magnesium hydroxide is hexagonal. 

  • It is a non-flammable compound. 

Reactions and Uses

The production of magnesium hydroxide takes place by the combination of the magnesium salts with alkaline water and magnesium hydroxide being very lowly soluble in water it is separated by precipitation. The reactions for this production methods are given below with the chemical formula for magnesium hydroxide/molecular formula of magnesium hydroxide and other compounds:

Mg\[^{2+}\] + 2OH\[^{-}\] → Mg(OH)\[_{2}\]

The above-mentioned equation is the best way to write the formula of magnesium hydroxide while also depicting the ionic forms of the component molecules. 


The industrial production of magnesium hydroxide is done by the treatment of seawater with lime which is Ca(OH)\[_{2}\]. Both of them can be separated easily as calcium hydroxide is more soluble in water than magnesium hydroxide which has very little solubility in water and as it precipitates as a solid. The reactions of this production method are given below:

MgO + H\[_{2}\]O → Mg(OH)\[_{2}\]

One of the most common uses of magnesium hydroxide is the industrial production of magnesium oxide, commonly known as magnesia which is important as it has dual characteristics of poor electrical conductivity and high thermal conductivity. It is easy to understand that MgO can be obtained from magnesium hydroxide when you write the chemical formula of magnesium hydroxide.


One of the most common uses of magnesium hydroxide is its day to day use in suspension either in the form of an antacid or a laxative. The compound works by the simple neutralisation reaction by which the hydroxide ions, that come from the magnesium hydroxide, combine with the H\[^{+}\] ions, that come from the hydrochloric acid that is produced by the parietal cells in the stomach, to form water. 


Magnesium hydroxide is directly ingestible by the foods and is approved by the food control administration across the world. It has been marketed for use in medical use in the form of chewable tablets, as capsules, powder, and in the form of liquid suspensions, also available in different flavours. It is also used as an antiperspirant. People also use magnesium hydroxide for the treatment of canker sores (aphthous ulcer) when it is used topically. It is also used for industrial neutralization of acidic waters and the mineral form of the compound as a fire retardant.

FAQs (Frequently Asked Questions)

1. What is Magnesium Hydroxide Used for?

Ans: Magnesium hydroxide is known to aid in controlling indigestion and heartburn. It is known to reduce stomach acid and increases the water content in the intestines that induces bowel movement. Thus, it is also used as a laxative to cure occasional constipation.

2. Can Magnesium Hydroxide Kill You?

Ans: Although the cases of magnesium hydroxide toxicity are rare it is known to cause severe nausea, vomiting, or diarrhoea. Also, if you do not observe any bowel movements if it has been used as a laxative. Sometimes there can be some rectal bleeding. In all such cases, after ingestion of magnesium hydroxide, a doctor or a physician should be consulted as soon as possible.

3. Is it Safe to Take Milk of Magnesia Daily?

Ans: The use of milk of magnesia or magnesium hydroxide is safe and can be taken daily under supervision. It can be used to deal with problems of occasional constipation, heartburn or dyspepsia. The common side effect observed by the patients is diarrhoea which can be a desired outcome for patients suffering from constipation.