Is HBr a Strong Acid

Let us know today about Is HBr a Strong Acid. In this article we will find out more about the acidity of HBr. We know that it is an inorganic compound and a diatomic molecule containing hydrogen and bromine as atoms.

Now let us try to answer the above questions and try to find out whether hbr is an acid or not.

Why is HBr acid?

In order to guess whether HBr is an acid, we first need to know what the criteria are for a substance to have properties to be called an acid. So what are acids in general? Acid is a substance (molecule or ion) that has the ability to accept a proton or can also be said to be able to accept a pair of electrons (in reactions).

Or we can also say that an acid when dissolved in solution (aqueous) gives H+ ions and gives H3O+ ions. So now coming to HBr, it is observed that when HBr is dissolved/added in solution (aqueous), dissociation of ions into H+ and Br- takes place. And then H+ (ion) readily combines with H2O molecule to give H3O+.

Well, it can be said that HBr is increasing the H+ concentration in the dissolved solution. According to Arrhenius an acid will increase the concentration of H+ (ion) when dissolved in a solution (aqueous). So, is it not following the acid principle (Arrhenius) discussed above? Yes, it follows so we can say that HBr is an acid.

Is HBr always an acid?

There are different concepts of acid and base, but we are going to take a look at some of them:

  • By definition of the solvent system an acid is a molecule (or species) that increases the cation concentration of a solvent and a base is a molecule that increases the ionic concentration of a solvent, so what do you think HBr from the above In which category will the discussed category fall?
  • As we know that H+ is the smallest cation and its species (H+ and Br-) dissociate when dissolved in aqueous solution, so yes it will increase the concentration of the cation and it is an acid.
  • Usanovich concept of acid and base: According to this concept an acid is a molecule (or species) which when reacted with a base gives cation or has the ability to accept electrons.
  • And base is called that molecule which reacts with acid to give anion. So we know that HBr reacts with a base and leaves H+ ions (which are cations), yet it is an acid .

So till now we have seen Arrhenius principle, solvent system concept, Usanovich concept and in all of them HBr is an acid, so we can conclude that HBr is always an acid. And in further topics other methods like Lewis acid and Brnsted acid are discussed which will give a more clear picture about the acidity of HBr.

Is HBr strong or weak acid?

HBr is a strong acid and not a weak acid. So what are the conditions for the acid to be strong?

It is said that if an acid is able to undergo complete dissociation and ionization when dissolved/mixed in aqueous solution then it is a strong acid. An acid will have a high potential to lose its proton (H+) and then water takes up the proton and forms the hydronium ion.

Strong acids are said to have small pka values ​​(logarithmic constant) but a high Ka value (i.e. dissociation constant of an acid). The reasons for HBr being a strong acid are discussed below:

  • The pka value (i.e. it’s logarithmic constant) is -9 and therefore it is able to completely ionize and give a proton (in aqueous form). The strong acid character arises as a result of the covalent bond (weak in nature) between H and H. Br atom.
  • Another reason for the strong acidic behavior of HBr is the significantly smaller difference in the size of the orbital (i.e. 1s and 4p) due to the overlapping of H and Br atoms that reduces the bond strength between H-Br ( which can be easily broken).
  • Note: The negative charge is seen to be diffused on the orbital (4p orbital), so the Br- ion is found to be comparatively stable. And this leads to a decrease in the charge density, making the dissociation constant (for HBr) much higher.

Given below are some factors that determine the strength of an acid:

  • With increase in atomic radius, acidity also increases. The atomic radius of HBr is found to be about 0.80 + – 0.11 which is quite high.
  • If the conjugate base is more electronegative then the acidic property also increases.

Hence HBr is a strong acid or we can say that it has strong acidic behavior.

Is HBr Lewis acid or Bronsted acid?

To predict well whether HBr is a Lewis acid or a Brnsted acid, we first need to know about Lewis acids and Brnsted acids in general.

Considering the Lewis concept: An acid is a molecule (species) that accepts a pair of electrons. An atom of a molecule (or species) must have an empty orbital (at least one) in its valence shell in order to be called a Lewis acid.

Summary of Lewis Acids :

  • Species which have an incomplete octet in their central atom or we can also say that these compounds lack electron.
  • Species whose central atom has a vacant d-orbital
  • All cations are assumed to be Lewis acids, with the smallest cation H+ (anion) acting as the stronger Lewis acid.

Now taking into account the Bronsted acid:

It is believed that the species that has the ability to donate protons is called Brnsted acid. And its conjugate base is the species that is formed once the acid donates a proton.

After understanding the concept of Lewis acid and Bronsted acid it can be said that HBr is a Lewis acid as it has the ability to accept a lone pair (one) in the process of combining with a water molecule and is also a Bronsted acid Because it is capable of losing the H+ (ion) and forming a base (known as the acid’s conjugate base).

Did I just confuse you? I come to the point that HBr can act as a Bronsted acid and a Lewis acid, as it is observed that most of the times a Bronsted acid is also a Lewis acid. But not always a Lewis acid can be a Brnsted acid.

Is HBr a binary acid?

Binary acids (or also known as hydracids) are molecules (or compounds) that have hydrogen-bonded (or we can say combined) with another element which is mostly non-metal in nature. So, yes HBr is a binary acid because the hydrogen in the HBr molecule is bound to bromine which has a non-metallic character.

Is HBr a strong acid in aqueous solution?

As we know that in aqueous solution HBr is a diatomic molecule and when dissolved in water gives a strong acid. 

After a period of boiling (constant) we get an aqueous solution of HBr (observed for distillate = 124.3 °C). The pH value is 1.602 (HBr solution is assumed to be 0.025 M). Hence, we can conclude that yes HBr is a strong acid in aqueous solution.

Is HBr stronger than HCl?

As we know that both HBr and HCl are binary acids (meaning hydrogen atom is bonded to an element which is nonmetal in nature).

It is observed that the bond between H–Br is longer (longer) than H–Cl bond, also Br is much larger than Cl hence HBr is a stronger acid than HCl.

So what happens is HBr is able to ionize completely and significantly more easily than HCl (this is because of the longer bond length). Meaning HBr is able to produce more H+ (ions) than HCl. Hence, we can conclude that HBr is stronger than HCl.

Is HBr a strong or a weak nucleophile?

A molecule must have (or act) as a Lewis base in order to act as a nucleophile. So, what is a Lewis base? A Lewis basis concept is that molecules have an unpaired pair of electrons in their energy levels:

  • Considering almost all ions, the greater the charge density, the greater the strength of the base.
  • (Alkynes or Alkynes) can form bonds (coordination) with metal ions and CO, C6H6 etc., which are seen to form complexes with the transition metal.

Now after understanding the Lewis base concept it is clear that HBr does not obey any criteria and is a Lewis acid. There is little or no scope for HBr to act as a Lewis base, which is the primary condition for a molecule to act as a nucleophile. 

Therefore it is not possible for HBr to donate electrons before donating protons. Hence we can conclude that HBr will not act as a nucleophile.

Isn’t HBr an electrophile?

Yes HBr is called an electrophile. So, let us now analyze how.

In the reaction between HBr and an alkene, HBr will act like an electrophile, so what happens is the electron of the reacting alkene reacts with the H+ (ion) of HBr.

The reason for this reaction is that the Br atom is able to remove electrons from the hydrogen atom because it is partially negatively charged. Therefore hydrogen becomes electrophilic. In conclusion HBr is an electrophile and not a nucleophile.

Frequently Asked Question

Which is the strongest acid?

Strong Acid:- Acids which produce a large number of + are called strong acids. For example, good luck etc. Weak Acids: Acids which produce a small number of + are called weak acids. For example, acetic acid, carbonic acid warfare etc.

Which is not a strong acid?

Among the given options, H₂CO₃ is not a strong acid. H₂CO₃ i.e. carbolic acid is a weak acid. Weak acids are those acids which produce a small number of cations (+). Acetic (CH₃COOH) and carbolic acid (H₂CO₃ etc.).

Which is the strongest reducing agent between HF HCl, HBr and HI?

In halogenated acids, the longer the H-X bond, the lower its bond energy and the greater the tendency to give H+, that is, it is a stronger acid.

Which is a weak acid?

A weak acid is an acid that ionizes only slightly in aqueous solution. Acetic acid or CH3COOH is a very common weak acid because it is not employed much in solution. HCl, HNO3, H2SO4 are strong acids.

Which is the stronger acid between HF and HCl and why?

HF < HCl < HBr < HI is the correct increasing order of acidic strength. Acidic strength is the tendency of an acid to dissociate into a proton, H+ and an ion. A strong acid is completely ionized in a solution and a weak acid is only partially ionised. The polarity of the hydrogen-atomic bond determines the strength of the acid.

What is strong and weak acid?

Strong acid is an acid which completely ionizes in water to form H’ ion which dissolves in water to form hydronium ion (H2O). A weak acid is an acid which partially ionizes in water to form hydronium ion (H2O). Strong acids- hydrochloric acid, nitric acid, formic acid, sulfuric acid.

What is the difference between a strong acid and a weak acid?

Strong Acids: Acids which ionize to a large extent are called strong acids. They have high concentration of H+. Weak Acids: Acids which ionize to a low potential and produce H+(aq) ions in small amounts are called weak acids.

Which is the weakest acid?

Carbonic acid is the weakest acid among these. It is also used in the manufacture of bubbly beverages, pharmaceuticals, cosmetics, fertilizers, food processing, anesthetics, etc. It is soluble in water. The chemical formula of carbonic acid is H2CO3.

What is the pH value of a salt made up of a strong acid and a weak base?

What is the pH value of a salt made up of a strong acid and a weak base? – Quora. What is the pH value of a salt made up of a strong acid and a weak base? Aqueous solutions of NH4Cl, FeCl2, CuSO4, AlCl3 etc. are acidic and the pH of the solution is less than 7.