Barium bromide
Encyclopedia
Barium bromide is the chemical compound
with the formula
BaBr2. Like barium chloride
, it dissolves well in water and is toxic in aqueous solution
.
motif, giving white orthorhombic crystals which are deliquescent.
In aqueous solution BaBr2 behaves as a simple salt
.
Barium bromide reacts with the sulfate
ion
from sulfuric acid
to produce a precipitate of barium sulfate
.
Similar reactions occur with oxalic acid
, hydrofluoric acid
, and phosphoric acid
.
or barium carbonate
via reaction with hydrobromic acid
to give hydrated barium bromide. This happens over a short period of time
Barium bromide can be crystallized
out from the solution in its dihydrate
form, BaBr2·2H2O, which gives the anhydrous
form upon heating to 120 °C.
s.
Historically, barium bromide was used to purify radium
in a process of fractional crystallization
devised by Marie Curie
. Since radium precipitates preferentially in a solution of barium bromide, the ratio of radium to barium in the precipitate would be higher than the ratio in the solution.
Chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
with the formula
Chemical formula
A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....
BaBr2. Like barium chloride
Barium chloride
Barium chloride is the inorganic compound with the formula BaCl2. It is one of the most common water-soluble salts of barium. Like other barium salts, it is toxic and imparts a yellow-green coloration to a flame. It is also hygroscopic....
, it dissolves well in water and is toxic in aqueous solution
Aqueous solution
An aqueous solution is a solution in which the solvent is water. It is usually shown in chemical equations by appending aq to the relevant formula, such as NaCl. The word aqueous means pertaining to, related to, similar to, or dissolved in water...
.
Structure and properties
BaBr2 crystallizes in a lead chlorideLead chloride
Lead chloride may refer to:* Lead chloride , mineral name: cotunnite.* Lead chloride...
motif, giving white orthorhombic crystals which are deliquescent.
In aqueous solution BaBr2 behaves as a simple salt
Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...
.
Barium bromide reacts with the sulfate
Sulfate
In inorganic chemistry, a sulfate is a salt of sulfuric acid.-Chemical properties:...
ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...
from sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...
to produce a precipitate of barium sulfate
Barium sulfate
Barium sulfate is the inorganic compound with the chemical formula BaSO4. It is a white crystalline solid that is odorless and insoluble in water. It occurs as the mineral barite, which is the main commercial source of barium and materials prepared from it...
.
- BaBr2(aq) + SO42-SulfateIn inorganic chemistry, a sulfate is a salt of sulfuric acid.-Chemical properties:...
→ BaSO4(sSolidSolid is one of the three classical states of matter . It is characterized by structural rigidity and resistance to changes of shape or volume. Unlike a liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire volume available to it like a...
) + 2 Br-BromideA bromide is a chemical compound containing bromide ion, that is bromine atom with effective charge of −1. The class name can include ionic compounds such as caesium bromide or covalent compounds such as sulfur dibromide.-Natural occurrence:...
(aq)
Similar reactions occur with oxalic acid
Oxalic acid
Oxalic acid is an organic compound with the formula H2C2O4. This colourless solid is a dicarboxylic acid. In terms of acid strength, it is about 3,000 times stronger than acetic acid. Oxalic acid is a reducing agent and its conjugate base, known as oxalate , is a chelating agent for metal cations...
, hydrofluoric acid
Hydrofluoric acid
Hydrofluoric acid is a solution of hydrogen fluoride in water. It is a valued source of fluorine and is the precursor to numerous pharmaceuticals such as fluoxetine and diverse materials such as PTFE ....
, and phosphoric acid
Phosphoric acid
Phosphoric acid, also known as orthophosphoric acid or phosphoric acid, is a mineral acid having the chemical formula H3PO4. Orthophosphoric acid molecules can combine with themselves to form a variety of compounds which are also referred to as phosphoric acids, but in a more general way...
.
Preparation
Barium bromide can be prepared from barium sulfideBarium sulfide
Barium sulfide is the inorganic compound with the formula BaS. BaS is an important precursor to other barium compounds including BaCO3 and the pigment lithopone, ZnS/BaSO4. Like other chalcogenides of the alkaline earth metals, BaS is a short wavelength emitters for electronic displays...
or barium carbonate
Barium carbonate
Barium carbonate , also known as witherite, is a chemical compound used in rat poison, bricks, ceramic glazes and cement.Witherite crystallizes in the orthorhombic system...
via reaction with hydrobromic acid
Hydrobromic acid
Hydrobromic acid is a strong acid formed by dissolving the diatomic molecule hydrogen bromide in water. "Constant boiling" hydrobromic acid is an aqueous solution that distills at 124.3 °C and contains 47.6% HBr by weight, which is 8.89 mol/L. Hydrobromic acid has a pKa of −9, making it a...
to give hydrated barium bromide. This happens over a short period of time
- BaS + HBrHydrobromic acidHydrobromic acid is a strong acid formed by dissolving the diatomic molecule hydrogen bromide in water. "Constant boiling" hydrobromic acid is an aqueous solution that distills at 124.3 °C and contains 47.6% HBr by weight, which is 8.89 mol/L. Hydrobromic acid has a pKa of −9, making it a...
→ BaBr2 + H2SHydrogen sulfideHydrogen sulfide is the chemical compound with the formula . It is a colorless, very poisonous, flammable gas with the characteristic foul odor of expired eggs perceptible at concentrations as low as 0.00047 parts per million... - BaCO3 + HBrHydrobromic acidHydrobromic acid is a strong acid formed by dissolving the diatomic molecule hydrogen bromide in water. "Constant boiling" hydrobromic acid is an aqueous solution that distills at 124.3 °C and contains 47.6% HBr by weight, which is 8.89 mol/L. Hydrobromic acid has a pKa of −9, making it a...
→ BaBr2 + CO2Carbon dioxideCarbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
+ H2OWaterWater is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
Barium bromide can be crystallized
Crystallization
Crystallization is the process of formation of solid crystals precipitating from a solution, melt or more rarely deposited directly from a gas. Crystallization is also a chemical solid–liquid separation technique, in which mass transfer of a solute from the liquid solution to a pure solid...
out from the solution in its dihydrate
Hydrate
Hydrate is a term used in inorganic chemistry and organic chemistry to indicate that a substance contains water. The chemical state of the water varies widely between hydrates, some of which were so labeled before their chemical structure was understood....
form, BaBr2·2H2O, which gives the anhydrous
Anhydrous
As a general term, a substance is said to be anhydrous if it contains no water. The way of achieving the anhydrous form differs from one substance to another...
form upon heating to 120 °C.
Uses
Barium bromide is a precursor to chemicals used in photography and to other bromideBromide
A bromide is a chemical compound containing bromide ion, that is bromine atom with effective charge of −1. The class name can include ionic compounds such as caesium bromide or covalent compounds such as sulfur dibromide.-Natural occurrence:...
s.
Historically, barium bromide was used to purify radium
Radium
Radium is a chemical element with atomic number 88, represented by the symbol Ra. Radium is an almost pure-white alkaline earth metal, but it readily oxidizes on exposure to air, becoming black in color. All isotopes of radium are highly radioactive, with the most stable isotope being radium-226,...
in a process of fractional crystallization
Fractional crystallization (chemistry)
In chemistry, fractional crystallization is a method of refining substances based on differences in solubility. If a mixture of two or more substances in solution is allowed to crystallize, for example by allowing the temperature of the solution to decrease, the precipitate will contain more of...
devised by Marie Curie
Marie Curie
Marie Skłodowska-Curie was a physicist and chemist famous for her pioneering research on radioactivity. She was the first person honored with two Nobel Prizes—in physics and chemistry...
. Since radium precipitates preferentially in a solution of barium bromide, the ratio of radium to barium in the precipitate would be higher than the ratio in the solution.