Discover

'Properties'

'General'
Name	Magnesium hydroxide
Chemical formula	Mg(OH)2
Molar mass	58.33 g/mol
Appearance	White solid
'Physical'
Melting point	Decomposes at 623 K (350 °C)
pKb	-0.85
Density	2.4 g/cm³
Crystal structure	?
Solubility	0.0012 g in 100 g water
'Thermochemistry'
ΔfH0gas	-561 kJ/mol
ΔfH0solid	-925 kJ/mol
S0solid	63 J/(mol·K)
'Safety'
Ingestion	Safe in small amounts, but large amounts can be dangerous.
Inhalation	May cause irritation.
Skin	May cause irritation.
Eyes	May cause irritation.
More info	Hazardous Chemical Database
SI units were used where possible. Unless otherwise stated, standard conditions were used. Disclaimer and references

'Magnesium hydroxide', Mg(OH)₂, otherwise known as milk of magnesia, is commonly used as an antacid or a laxative. The mineral form of magnesium hydroxide is known as brucite. Magnesium hydroxide interferes with the absorption of folic acid and iron. The diarrhea caused by magnesium hydroxide carries away much of the body's supply of potassium, and failure to take extra potassium will lead to muscle cramps.
It has very low solubility in water, and has a K_sp value of 1.5x10^-11.
It does not completely dissociate and therefore is a weak base.

Contents

Preparation

Uses

External links

Preparation

From a Magnesium salt:
:$Mg\_3N\_\{2(s)\}\; +\; 6H\_2O\_\{(l)\}$
ightarrow 2NH_{3(g)} + 3Mg(OH)_{2(aq)}
:In words:
:Solid Magnesium nitride + Water = Ammonia + Aqueous Magnesium Hydroxide
From a Magnesium base:
:$MgO\_\{(s)\}\; +\; H\_2O\_\{(l)\}$
ightarrow Mg(OH)_{2(aq)}
:In words:
:Solid Magnesium oxide + Water = Aqueous Magnesium Hydroxide
From pure Magnesium metal:
:$Mg\_\{(s)\}\; +\; 2H\_2O\_\{(g)\}$
ightarrow Mg(OH)_{2(aq)} + H_{2(g)}
:In Words:
:Solid Magnesium + Water = Aqueous Magnesium Hydroxide + Hydrogen Gas

Uses

Magnesium hydroxide is used as an antacid to neutralize stomach acid. In industries, it is used as a non-hazardous alkali to neutralise acidic wastewaters. In addition, magnesium hydroxide, better known as its common name ''Milk of Magnesia'' can be used as an armpit deodorant or antiperspirant. It is also used in bleaching solutions to whiten clothes.

External links