Important description of HCl acid including properties-preparation-application

Important description of HCl acid in chemistry 

HCl acid is also known as muriatic acid, is a chemical compound of hydrogen and chlorine with molecular formula, HCl. 

It is polar covalent compound. The dipole moment of H–Cl acid is 1.03 Dbye.

The another name of HCl acid are hydrogen chloride, chlorane, spirits of salt, hydronium chloride etc.

HCl acid is a strong mono basic weak acid. The pKa value ofHCl acid is –7. The 100 ml concentrated HCl acid solution contains 39 ml of pure HCl.

The calculated density of concentrated HCl acid is 1.2 g/c.c. Although, HCl acid is a covalent hydride of hydrogen yet it has some ionic character due to high electronegativity of chlorine atom.

Important properties HCl acid in chemistry

Physical state

HCl acid is a gas at room temperature. Because HCl acid can’t form hydrogen bond due to less polarity of  H – Cl bond.

But it is easily compressed to colorless liquid under low temperature and high pressure. The liquid form of HCl gas is known as HCl acid.

Melting and boiling point of HCl acid

The melting and boiling point of HCl acid are, –114ᵒC and –84ᵒC respectively. Due to less polarity of H–Cl bond, HCl acid does not form inter molecular hydrogen bonding. 

That is, HCl molecules remain as an individual molecule. Consequently, the melting point and boiling point of HCl acid is less than HBr and HI acids.

Bond dissociation energy and stability

Chlorine is a strong electronegative element than hydrogen. So, H–Cl bond is more polar and more strong than  H–Br and H–I bond.

Hence, the bond dissociation energy of H–Cl bond is higher than that of H–Br and H–I bond.

The bond dissociation of H – Cl bond is 103 Kcal/mole, which is higher than that of HBr and HI.

So, the H – Cl bond does not dissociate easily. Hence, HCl is thermally more stable than HBr and HI.

Reducing properties of HCl acid

Since the bond dissociation energy of H–Cl bond is higher than H–Br and H–I bond, hence HCl acid is a mild reducing agents.

But some oxidizing agent, such as KMnO4, K2Cr2O7 Pb3O4, PbO2etc, oxidize HCl acid to release chlorine gas.

What is the cause of HCl acid strength ?

It has been experimentally found that HCl acid is a strong acid. The HCl acid solution change the litmus paper color from blue to red.In aqueous solution, HCl acid is dissociated into the following ions, H₃O+ and Cl^–.

Now, HCl acid is reacts with metallic carbonate or bicarbonate and evolved a effervescence of colorless CO₂ gas.

Besides, HCl acid reacts with metal oxide and hydroxide to form salt and water.

The above reaction proved that HCl is a strong acid which is also supported by the pKa value of HCl acid [pKa = –7].

HCl acid preparation in laboratory

When a mixture of NaCl and concentrated H₂SO₄ is heated at different temperature, then hydrogen chloride is obtained.

This preparation method consisting of two step. In the first step, NaCl react with H₂SO₄ at 150ᵒ-200ᵒC temperature, produced NaHSO₄ and HCl.

In the second step, the rest of the NaCl reacts with the producing NaHSO₄  under  500ᵒ-600ᵒC temperature and produce the expected HCl gas.

When HCl gas is dissolved in water, then HCl acid is prepared.

Industrial method for preparation of HCl acid

HCl acid is also prepared industrially by heating a mixture of equimolecular H₂ and Cl₂ gas.

This is the large scale preparation method of HCl acid in the world.

HCl acid application in chemistry

 HCl acid is an important chemical in chemistry. So, HCl acid has a significant role both in organic and in inorganicchemistry.

HCl acid is very important in industrial production of different goods.  Some important application of HCl acid is discussed below.

Important application as a laboratory reagent

HCl acid is used as an important laboratory reagent. It is used as a reducing agent, catalytic reagent, hydrolyzing agent, in the preparation and identification of many organic compounds.

For example, anhydrous ZnCl2 and concentrated HCl acid mixture[which is known as Luis reagent],is used for identification of primary, secondary and tertiary aliphatic alcohol.

Important application of HCl acid in industrial purpose

HCl acid is used in industrial production of some important substance, such as, Cl₂, NH₄Cl, glucose etc.

 Again, in galvanization process, HCl acid is used as a cleaning substance. It is used to clean iron sheet before tin plating or galvanization.

Most important use of HCl acid is in the dyeing industry, in the medicine production industry and in sugar industry.

The mixture of concentrated HCl acid and concentrated HNO3 in 3: 1 ratio[ known as aqua regia ], is used as a melting agent of gold, silver etc in industry.

 HCl is used in to prepare of chlorine gas

 HCl acid is used to prepare Cl₂ gas, oxidizing it by air oxygen in presence of CuCl₂ catalyst in Deacon’s process.

Cl₂ gas is also produced on hydrolysis of concentrated HCl acid, in reaction with some  electro-positive metals [ Zn, Mg, Ca etc ].

Others application of HCl acid.

Beside the above uses, HCl acid is used in industry for removal of lubricants from animal bone and also use for its purification.

HCl acid is used to prepare many organic compounds, such as alkyl chloride from alkene and alcohol and glucose, fructose from sugar.

Important description of HCl acid in chemistry

Important properties HCl acid in chemistry

Melting and boiling point of HCl acid

Bond dissociation energy and stability

Reducing properties of HCl acid

What is the cause of HCl acid strength?

HCl acid preparation in laboratory

HCl acid application in chemistry

Important application as a laboratory reagent

Important application of HCl acid in industrial purpose

HCl is used in to prepare of chlorine gas

Read more: Strength of HF acid and other details

HF acid-properties-strength-pH calculation

Important properties of HF acid in chemistry

Hydrofluoric acid is also known as hydrogen fluoride gas which is a chemical compound of hydrogen and fluorine with molecular formula, HF. 

Hydrogen fluoride gas is highly soluble in water.The concentrated aqueous solution of hydrogen fluoride gas is known as hydrofluoric acid.

Uses of hydrofluoric acid with health effect.

Important Uses of hydrofluoric acid in chemistry

Hydrofluoric acid is a concentrated aqueous solution of hydrogen chloride, with chemical formula, HF. Density of hydrofluoric acid 1.15 g/c.c.

 It is a polar covalent compound. The dipole moment of H–F bond is 1.86 D. Hydrofluoric acid is a colorless, highly poisonous mono basic weak acid.

The melting and boiling point of hydrofluoric acid are, –83.6 ᵒC and 19.5 ᵒC respectively.

Although, hydrofluoric acid is a poisonous acid yet it has many chemical. Most amount of HF acid is used in industrialproduction.

Some important uses of hydrofluoric acid in chemistry is discussed below.

Use of hydrofluoric acid as non aqueous solvent

Hydrofluoric acid is one of the most water like solvents because, it is liquid at temperatures below 19.5 ᵒC upto –89.5 ᵒC.

The boiling point of hydrofluoric acid is very high with respect to other non aqueous solvent. Because of its high dielectric constant, it is used as a excellent ionizing solvent.

But the use of hydrofluoric acid as non aqueous solvent is limited due its high poisonous nature.Few important chemical reaction taking place in hydrofluoric acid medium are,

Which one has more lattice energy, Na3N or NaF ?

Which one has more lattice energy, Na₃N or NaF ?

In case of Na₃F and NaF molecules, cations are same but anions are different [ N^3-, F^– ] .It is experimentally proved that the radius of N^3– ions is greater than F^– ion.

Now, lattice energy is directly proportional to the multiple of ionic charge and inversely proportional to the radius of cation and anion.

So, the lattice energy of  NaF should be greater than that of Na₃N compound. But, actually the order of lattice energy of NaF and Na₃N compound is reversed.

Because, in calculation of lattice energy of ionic compounds , the extent of ionic charge is more effective than ionic radius.

Since the ionic charge of N^3-ion is greater than F^–, hence Na₃N compound has high lattice energy than NaF .

The value of lattice energy of Na₃N is –4422 kj/mole and that of NaF is –923 Kj/mole.

        Read more: Which one has higher lattice energy, MgF2,CaF2 or ZrO2 ?

        Read more : Lattice energy calculation for ZrO₂ molecule

Calculation of lattice energy of Na₃N compound 

Lattice energy of Na₃N compound can be calculated indirectly by applying Born-Haber cycle. The Born-Haber cycle of Na₃N compound is shown below.

According to the Born-Haber cycle of Na₃N compound, we can write a relation among  enthalpy of formation of Na3N,electron affinity and bond dissociation of nitrogen, ionization energy and sublimation energy of sodium and lattice energy released are, 

                  ΔH_f   =  S  + [3 x I.E] + [ I.E₁ + I.E₂ + I.E₃ ] + ½ D + U

           Or,    - 20  = 322  + 1488  +  2120  +  472  + U

            Or,   U =  – 4422 Kj/mole

Therefore, the lattice energy of Na₃N compound is –4422 kJ/mole.

activating groups-explanation-list with application

Activating groups explanation with an example.

Activating groups are those groups which increase the density of electron of benzene ring due to their positive inductive effect and resonance effect.

Since these type of groups increase the electron density of benzene ring, 
that is, activate the benzene ring, hence they are called activator enhancer or activating group.

So, due to presence of activating group, the benzene ring becomes more activate towards electrophilic substitution reaction.

For example, phenol with – OH activatinggroup under goes electrophilic substitution reaction more easily than benzene.

The central atom of activating group which directly attached to the benzene ring, contain one or more lone pair of electron.

 Read more: Why are Xenon fluorides act as a strong oxidizing agents?  

 Read more: Octetexpansion of Xenon fluorides

So, due to their +R effect, they increase electron density basically, on the ortho and para carbon atom in the benzene ring. Hence, activating groups are also called ortho and para directing groups.

Now, due to presence of activating group, the electrophile attack the benzene ring easily than unsubstituted benzene ring to form a ‘σ ‘- complex.

 Activating groups list or examples.

There are three types of activating groups, namely, strong activating groups, medium activating groups and weak activating groups.

A short  list of these three types of activating groups are shown below.

Lattice energy of MgF2-CaF2-ZrO2 molecule-explanation-calculation

·        Which one has higher lattice energy, MgF₂, CaF₂ or ZrO₂ ?

Lattice energy is directlyproportional to the multiple of ionic charge and inversely proportional to the radius of cation and anion.

In the above compounds, MgF₂, CaF₂ or ZrO₂ , the extent of charge on‘Mg’ ,’Ca’ and ‘Zr’ metal are, +2 ,+2 and +4 respectively.

Again, the extent of charge on ‘F’ and ‘O’ atoms are -1 and -2  respectively.

So, from the data of cationic and anionic charge, it is clear that the multiple of ionic charge for ZrO₂ is highest.

Hence, ZrO₂ molecule has higher lattice energy among all the above compounds.

The value of lattice energy of MgF2, CaF2and ZrO2 molecules are, -2913 Kj/mole , -2609 Kj/mole and  - 8714.5 kJ/ mole respectively.

Read more: Which one has more lattice energy, Na₃N or NaF?

Read more :Calculationof lattice energy of Na3N ?

·        Which one has higher lattice energy, MgF₂  or CaF₂ ?

In case of MgF₂ and CaF₂ molecule, the extent of charge on both ‘Mg’ and’ Ca’ metal is, +2 and the extent of charge on ‘F atom is, -1 .

That is, both cations and anions contain same extent of charge.

Now, both calcium and magnesium are group-II alkaline earth metal. It has been found that, the cationic size of group-II metal decreases from top to bottom.

Therefore, the radius of Mg²⁺ cation is less than Ca²⁺ cation.

Since, the lattice energy is directly proportional to the multiple of ionic charge 

and inversely proportional to the radius of cation and anion, hence MgF₂ has higher lattice energy than CaF₂.

The value of lattice energy of MgF2 and CaF2molecules are, -2913 Kj/mole , and -2609 Kj/mole respectively.

·        Why is the lattice energy of ZrO₂ so high ?

Lattice energy is directly proportional to the multiple of ionic charge and inversely proportional to the radius of cation and anion.

Now, in case of ZrO2 molecule, the extent of charge on ‘Zr’ metal atom is very much high, that is, +4 and hence the radius of Zr⁴⁺ cation is small.

Metal with high charge and small radius cause the high lattice energy.

Consequently,  the lattice energy of ZrO₂ so high.

The lattice energy of ZrO₂ molecule is about, –9714.5 Kj/mole.

Read more: Which one has more lattice energy, Na₃N or NaF?

Read more :Calculationof lattice energy of Na3N ?

·        Lattice energy calculation for ZrO₂ molecule

Lattice energy of ZrO₂ can be calculated indirectly by using Born-Haber cycle. 

The atomic number of oxygen and zirconium are 8 and 40 respectively.

Hence, the electronic configuration of  ‘O’ and ‘Zr’ are  [He]2s² 2p⁴ and [Kr] 4d² 5s² respectively.

The first and second electron affinities of oxygen atom is +141 kj/mole and – 770 kj/mole respectively. The bond dissociation energy of oxygen molecule is 498 kj/ mole.

The sublimation energy of Zr(s ) to Zr(g) change is 591 kj/mole and first, second , 

third and forth ionization energy of Zr are about 640 kj/mole, 1270 kj/mole, 2218 kj/mole and 3412 kj/mole respectively.

Xenon fluorides-xenon fluorides act as a strong oxidizing agent

Why are xenon fluorides act as a strong oxidizing agent ?

The ionization potential of noble gas elements are very much high due to their complete valence shell.

That is why, inert gas elements have no tendency to participate in chemical reactions. 

But, under certain condition ‘Xe’ and Kr form few fluorides as well as oxide compounds.

So, xenon fluorides have an affinity for electrons to regain inert gas configuration and hence, xenon fluorides act as very strong oxidizing reagent.

The oxidizing power of xenon fluoride compounds increase with increase in oxidation number of xenon(Xe) element.

For example, xenon hexa-fluoride[ XeF₆ ] is more stronger oxidizing than xenon di-fluoride[XeF₂ ].

There are some chemical reaction of xenon fluorides where xenon fluorides act as oxidizing substances .

Such as,xenon fluoride oxidized hydrogen to form HF molecule and Cl^–, I^– to Cl₂ and I₂ respectively.

 It also oxidized Ce(III) compounds to Ce(IV) compounds and Br(V) compound to Br(VII ) compound.

Octet expansion of xenon fluorides.

Xenon fluorides and also other xenon compounds does not obey octet rule.

All the xenon compounds including xenon fluorides show expansion of octet.

• Read more : What is activating groups in organic chemistry ?
  Why is phenol more activethan benzene towards electrophilic reaction?  

Summary :

Why are xenon fluorides act as a strong oxidizing substance ?

Octet expansion of xenon fluorides. 

Octet rule definition and limitation with examples.