MAGNESIUM HYDROXIDE is the inorganic compound with the chemical
formula Mg(OH)2. It occurs in nature as the mineral brucite . It is a
white solid with low solubility in water (Ksp = 5.61×10−12).
* 1 Preparation
* 2 Uses
* 2.1 Precursor to MgO
* 2.2 Health
* 2.2.1 Metabolism * 2.2.2 History of Milk of Magnesia
* 2.3 Other niche uses
* 2.3.1 Waste water treatment * 2.3.2 Fire retardant
* 3 Mineralogy * 4 References
Combining a solution of many magnesium salts with alkaline water induces precipitation of solid Mg(OH)2: Mg2+ + 2 OH− → Mg(OH)2
On a commercial scale, Mg(OH)2 is produced by treating seawater with lime (Ca(OH)2). 600 m3 of seawater gives about one ton of Mg(OH)2. Ca(OH)2 is far more soluble than Mg(OH)2, the latter precipitates as a solid: Mg2+ + Ca(OH)2 → Mg(OH)2 + Ca2+
PRECURSOR TO MGO
Most Mg(OH)2 that is produced industrially, as well as the small amount that is mined, is converted to fused magnesia (MgO). Magnesia is valuable because it is both a poor electrical conductor and an excellent thermal conductor.
When the patient drinks magnesium hydroxide, the suspension enters the stomach . Depending on how much was taken, one of two possible outcomes will occur.
As an antacid, magnesium hydroxide is dosed at approximately 0.5–1.5 g in adults and works by simple neutralization , where the hydroxide ions from the Mg(OH)2 combine with acidic H+ ions produced in the form of hydrochloric acid by parietal cells in the stomach to produce water.
As a laxative, magnesium hydroxide is dosed at 2–5 g, and works in a number of ways. First, Mg2+ is poorly absorbed from the intestinal tract, so it draws water from the surrounding tissue by . Not only does this increase in water content soften the feces, it also increases the volume of feces in the intestine (intraluminal volume) which naturally stimulates intestinal motility. Furthermore, Mg2+ ions cause the release of cholecystokinin (CCK), which results in intraluminal accumulation of water, electrolytes, and increased intestinal motility. Although it has been stated in some sources, the hydroxide ions themselves do not play a significant role in the laxative effects of milk of magnesia, as basic solutions (i.e., solutions of hydroxide ions) are not strongly laxative, and non-basic Mg2+ solutions, like MgSO4 , are equally strong laxatives mole for mole.
Only a small amount of the magnesium from magnesium hydroxide is usually absorbed by the intestine (unless they are deficient in magnesium). However, magnesium is mainly excreted by the kidneys so long-term, daily consumption of milk of magnesia by someone suffering from renal failure could lead in theory to hypermagnesemia .
History Of Milk Of Magnesia
On May 4, 1818, American inventor John Callen received a patent (No. X2952) for magnesium hydroxide. In 1829, Sir James Murray used a "condensed solution of fluid magnesia" preparation of his own design to treat the Lord Lieutenant of Ireland , the Marquis of Anglesey, of stomach pain. This was so successful (advertised in Australia and approved by the Royal College of Surgeons in 1838) that he was appointed resident physician to Anglesey and two subsequent Lords Lieutenant, and knighted. His fluid magnesia product was patented two years after his death in 1873.
The term milk of magnesia was first used by Charles Henry Phillips in 1872 for a suspension of magnesium hydroxide formulated at about 8%w/v . It was sold under the brand name Phillips' Milk of Magnesia for medicinal usage.
Although the name may at some point have been owned by
Some magnesium hydroxide products sold for antacid use (such as
OTHER NICHE USES
Natural magnesium hydroxide (brucite ) is used commercially as a fire retardant. Most industrially used magnesium hydroxide is produced synthetically. Like aluminium hydroxide, solid magnesium hydroxide has smoke suppressing and flame retardant properties. This property is attributable to the endothermic decomposition it undergoes at 332 °C (630 °F): Mg(OH)2 → MgO + H2O
The heat absorbed by the reaction retards the fire by delaying
ignition of the associated substance. The water released dilutes
combustible gases. Common uses of magnesium hydroxide as a flame
retardant include additives to cable insulation (i.e. cables for high
quality cars, submarines , the
Brucite, in which some of the Mg2+ cations have been substituted by Al3+ cations, becomes positively charged and constitutes the main basis of layered double hydroxide (LDH). LDH minerals as hydrotalcite are powerful anion sorbents but are relatively rare in nature.
For the same reason, dolostone cannot be used as construction aggregate for making concrete. The reaction of magnesium carbonate with the free alkali hydroxides present in the cement porewater also leads to the formation of expansive brucite. MgCO3 + 2 NaOH → Mg(OH)2 + Na2CO3
This reaction, one of the two main alkali-aggregate reaction (AAR) is also known as alkali-carbonate reaction .
* ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill,
2002, ISBN 0-07-049439-8
* ^ Toshiaki Enoki and Ikuji Tsujikawa (1975). "Magnetic Behaviours
of a Random Magnet, NipMg(1-p)(OH2)". J. Phys. Soc. Jpn. 39 (2):
317–323. doi :10.1143/JPSJ.39.317 .
* ^ A B Zumdahl, Steven S. (2009). Chemical Principles 6th Ed.
Houghton Mifflin Company. p. A22. ISBN 0-618-94690-X .
* ^ Handbook of Chemistry and Physics (76th ed.). CRC Press. ISBN
* ^ A B Margarete Seeger; Walter Otto; Wilhelm Flick; Friedrich
Bickelhaupt; Otto S. Akkerman (2005), "
* v * t * e
* MgB2 * MgBr2 * MgCO3 * MgC2O4 * MgC6H6O7 * MgC14H10O4 * MgCl2 * Mg(ClO4)2 * MgF2 * MgH2 * Mg(HCO3)2 * MgI2 * Mg(NO3)2 * MgO * MgO2 * Mg(OH)2 * MgPo * MgS * MgSO3 * MgSO4 * MgU2O7 * Mg2Al3 * Mg2Si * Mg2SiO4 * Mg2Si3O8 * Mg3N2 * Mg3(PO4)2 * Mg2(CrO4)2
* v * t * e
B C NH3.H2O O F Ne
Al(OH)3 Si P S Cl Ar
KOH Ca(OH)2 Sc(OH)3 Ti V Cr(OH)2 Cr(OH)3 Mn(OH)2 Fe(OH)2 Fe(OH)3 Co(OH)2 Ni(OH)2 CuOH Cu(OH)2 Zn(OH)2 Ga(OH)3 Ge(OH)2 As Se Br Kr
RbOH Sr(OH)2 Y(OH)3 Zr(OH)4 Nb Mo Tc Ru Rh Pd AgOH Cd(OH)2 In(OH)3 Sn(OH)2 Sn(OH)4 Sb(OH)3 Te I Xe
CsOH Ba(OH)2 * Hf Ta W Re Os Ir Pt Au(OH)3 Hg(OH)2 TlOH Tl(OH)3 Pb(OH)2 Pb(OH)4 Bi(OH)3 Po At Rn
Fr Ra ** Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og
* La(OH)3 Ce(OH)3 Pr(OH)3 Nd(OH)3 Pm(OH)3 Sm(OH)3 Eu(OH)3 Gd(OH)3 Tb(OH)3 Dy(OH)3 Ho(OH)3 Er(OH)3 Tm(OH)3 Yb(OH)3 Lu(OH)3
** Ac Th(OH)4 Pa UO2(OH)2 Np Pu Am Cm(OH)3 Bk Cf Es Fm Md No Lr
* v * t * e
Urologicals , including antispasmodics (G04B )
Urinary antispasmodics (primarily antimuscarinics )
* v * t * e
Drugs for acid related disorders: Antacids (A02A )
MAGNESIUM (INCREASES MOTILITY)
ALUMINIUM (DECREASES MOTILITY)
Combinations and complexes of aluminium, calcium and magnesium
* v * t * e
Drugs for constipation (laxatives and cathartics ) (A06 )
Links: ------ /wiki/Inorganic_compound