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Explain the significance of bond order. Can bond order be used for quantities comparisons of the strengths of chemical bonds?

Bond order is defined as half the difference between th electrons present in the bonding and the antibonding orbitals. Integral value of 1, 2, or 3 corresponds to single, double or triple bonds respectively as studied in classical concept. The bond order may be taken as an approximate measure of the bond strength. As the bond order increases bond length decreases and bond strength increases.

Why is dimethylformamide (DMF) a useful solvent?

DMF, HCONMe2 , is an aproric solvent (has no H for H-bonding) with a moderately high dielectric constant and a high dipole moment. Thus, although it dissolves many ionic compounds, DMF does not do so by forming  H-bonds with the anions. The salts are dissolved, chiefly through solvation of the cation by attraction to the end  of the C-O dipole. The + end of the dipole is shielded within the molecule and can solvate the anion very weakly, if at all.

Why not peroxide effect observed in case of addition of HCl or HI with alkene but it observed with HBr only?

The peroxide effect is not noted in the case of HCI or Hl. This is due to the fact that HCI bond is too strong to be broken to produce free radicals (430.5 kJ mol-1) than the HBr bond (363.7 kJ mol-1). Hl has a lower bond energy (296.8 kJ mol-1) and in case of the addition of HI although H-I bond is easily broken by homolysis, but the iodine atoms so produced immediately react to form iodine molecules rather than attacking the double bond of carbon atom in alkene. 
           °CH3 + HI -->. CH4 +  I°
             I° + I°---> I2

Which of the following is a strongest acid among oxy acids of chlorine and why? "HClO, HClO2, HClO3, HClO4"


According to Bronsted Lowery concept, a strong acid has weak conjugate base and vice versa. 

The given oxy acids of chlorine HCIO, HCIO2, HClO3 and HClO4 and their conjugate bases are CIO-, CIO2-, ClO3-, ClO4- respectively. These anions are stabilised to greater extent, due to the presence of π-bond and lone pair, if number of π-bond increase extent of stabilisation increase. In case of ClO- there is no π-bond hence if form less stable conjugate base hence act as weak acid while in case of ClO4- it has three pπ-dπ bond which stablised greater extent and form more stable conjugate base hence it conjugate acid (HClO4) is strongest acid. Oxy acids of chlorine and their number of pπ-dπ bonds given as:

HOCI (0~Pπ-dπ)

HOCIO (1~Pπ-dπ)

HOClO2 (2~Pπ-dπ)

HOCIO3 (3~Pπ-dπ)

Thus overall order of acidic strength of oxy acids of chlorine is as:



                  "HClO < HClO2 < HClO3 < HClO4



Related Questions:

  

How does the thermal stability of oxyacids of chlorine increase with an increase in the oxidation state of chlorine atom ?


The thermal stability of oxy acids of chlorine increase on increasing of oxidation number of chlorine atom because on addition of additional oxygen atoms, the number of (pπ-dπ) π-bonds increase which provide extra stability to the molecules. Oxy acids of chlorine and their number of pπ-dπ bonds given as:

HOCI (0~Pπ-dπ)

HOCIO (1~Pπ-dπ)

HOClO2 (2~Pπ-dπ)

HOCIO3 (3~Pπ-dπ)

Thus the overall stability of oxy acids of chlorine are given as:

                "HClO < HClO2 < HClO3 < HClO4

Related Questions:

What is the correct order of electronegativity of Cl atoms in HClO, HClO2, HClO3 and HClO4 ?


According to the question the oxidation states of Cl are in given series of oxy acids as follows:

HOCI (Chlorine +1 oxidation state) 

HOCIO (Chlorine +3 oxidation state) 

HOClO2 (Chlorine +5 oxidation state) 

HOCIO3 (Chlorine +7 oxidation state) 

The hydrogen is bonded to an oxygen rather than to the chlorine in the given oxy acids. Now It is clear that on addition of additional oxygen atoms with chlorine, it's oxidation state also Increases hence acidity as well as electronegativity both increase linearly.



We know that "Electronegativity is the property of pulling the bonding electron pair towards itself". Higher the oxidation state means more electrons attracted towards thus the atom has more oxidation state (+) is more electronegative.  So electronegativity of Cl follows:



                    "HCIO < HCIO2 < HClO3 < HClO4."

Why Chlorine (Cl2) bleaches a substance permanently but sulphuredioxide (SO2) does it temporarily?

Why Noble gases are mostly chemically inert?

The inertness to chemical reactivity of noble gases is attributed to the following reasons:

(1)The noble gases except helium (1s2) have completely filled ns2np6 electronic configuration in their valence shell.

(2) They have high ionisation enthalpy and more positive electron gain enthalpy.

Why Xenone (Xe) does not forms compounds such as xenone trifluoride (XeF3)and xenone pentafluoride (XeF5)?

By the promotion of one, two or three electrons from filled p-orbital to the vacant d-orbital in the valence shell, 2, 4 or 6 half filled orbitals are formed. Thus Xe can combine only with even number of fluorine and not odd.

Why Noble gases exhibit large positive values of electron gainenthalpy?

Since noble gases have stable electronic configurations, they have no tendency to accept the electron and therefore, have large positive values of electron gain enthalpy.

Why Noble gases have very low boiling points?

Noble gases being monoatomic have no interatomic forces except weak dispersion forces and therefore, they are liquefied at very low temperatures. Hence, they have low boiling points.

Why chlorine trifluoride (ClF3) exists but fluorine trichloride (FCl3) does not?

Hypophosphorous acid (H3PO2) and Phosphorous acid (H3PO3) act as as good reducing agents while H3PO4 does not.Why?

We know that In Hypo phosphorous acid (H3PO2) has two H atoms are bonded directly to P atom and In Phosphorous acid (H3PO3) has one H atom is bonded directly to P atom which imparts reducing character to the acid, whereas in H3PO4 there is no H atom bonded directly to P atom hence it does not have reducing character.

Related Questions:



Trisilyl amine, N(SiH3)3 is planar whereas trimethyl amines N(CH3)3 is pyramidal. Explain why?.















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