Hydrobromic-acid-formula-properties-uses with pH calculation

Hydrobromic acid is an important chemical in chemistry, especially in inorganic chemistry. It is polar covalent molecule with chemical formula, HBr.

The pKa value of HBr acid is -9. This means that hydrobromic acid is a strong mono basic hydracids and act as a strong reducing agent in many chemical reactions.

Hydrobromic acid is a diatomic molecule which consists of hydrogen and bromine. The chemical formula in aqueous solution and Lewis structure of hydrobromic acid are shown below.

Hydrobromic acid is a colorless with intense pungent smelling gas . It is slightly heavier than air and creates brown smoke with wet air.

Hydrobromic acid is highly soluble in water. When it dissolved in water, it forms a constant boiling mixture with boiling point 399K.

An aqueous solution of hydrobromic acid contains 70% of hydrogen bromide gas at 126ᵒC temperature. The density of hydrobromic acid is 1.49 g/ml.

The density of hydrobromic acid is 1.49 g/ml. That is, 1 ml aqueous solution of hydrobromic acid contains 1.49 g of HBr gas. Therefore, 1000 ml or 1 liter contains 1490 g of HBr gas.

Hence the strength of hydrobromic acid solution is [1490 / 80.91] = 18.4(M). Since hydrobromic acid is a strong acid , hence it is completely ionized in aqueous solution [HBr = H++ Br -].

Hydrogen bromide is a gas at room temperature. But it is easily compressed to colorless liquid.

HBr gas is slightly heavier than air . When it comes in contact with aquatic air it creates brown smoke.

T he melting point and boiling point of hydrobromic acid are, 185 K and 206 K respectively.

Due to less polarity of H-Br bond, hydrogen bromide can’t form inter molecular hydrogen bonding.

That is, HBr molecules remain as an individual molecule. Hence, HBr is a gas at room temperature.

Bromine is a electronegative element than hydrogen. So , hydrobromic acid is a polar covalent molecule.

The bond dissociation energy of H — Br molecule is 363 Kj/mole which is higher than HI molecule but less than HF and HCl molecules.

This means that HBr is thermally more stable than HI molecule but less stable than HF and HCl molecule.

Since the bond dissociation energy of H-Br bond is less than H-F and H-Cl bond, hence HBr acids act as a strong reducing agent .

Some oxidizing agent, such as KMnO 4, K 2Cr 2O 7 Pb 3O 4, PbO 2 etc, oxidize HBr acid to release bromine gas.

Hydrobromic acid reaction with metals

Some metals which are electropositive than hydrogen, react with dilute HBr and produced

For example, zinc, magnesium, iron, calcium etc

Hydrobromic acid is a strong mono basic acid. It is mores stronger acid than HF or HCl. Because, HBr acid is ionized in aqueous solution completely.

The aqueous solution of hydrobromic acid changes the litmus paper color from blue to red. It reacts with metal oxide or hydroxide to form salt and water.

This is two step process reactions. In the first step, bromine reacts with red ‘P’ to form phosphorous tri bromide and phosphorous penta bromide.

In the second step, the producing phosphorous tribromide and phosphorous pentabromide under goes hydrolysis, resulting in the formation of bromide gas.

This hydrogen bromide gas produces hydrobromic acid when dissolved in water solvent.

When a mixture of hydrogen gas and bromine vapor is passed over ‘Pt’ catalyst at 473 K temperature, then hydrogen bromide gas is obtained.

This method for preparation of hydrogen bromide gas is known as Synthesis method. On dissolving of this hydrogen bromide gas in water, hydrobromic acid is prepared.

Hydrobromic acid play an important role in inorganic, organic and also in industrial chemistry. Some application of HBr acid is discussed below.

The silver salt of HBr acid is used in photography.

In organic chemistry, hydrobromic acid is used to prepare bromo compound, Such as, bromo alkane, alkyl magnesium bromide, bromo benzene and other aromatic benzene derivative compound.

It is used as a reducing agent both in organic and inorganic chemistry. It is also used as a laboratory reagent.

When a mixture of concentrated HBr acid and a little amount of concentrated sulfuric acid are heated in a test tube, a brown color of gas with pungent smell is evolved.

This emitted gas change the color of KI in starch solution, from brown to blue. This is best identification method of .

Hydrobromic acid chemical formula and Lewis structure.

Hydrobromic acid uses in chemistry.

Identification of hydrobromic acid.

Originally published at https://chemizi.blogspot.com.