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.
Saturday, February 29, 2020
Friday, February 28, 2020
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
Sunday, February 23, 2020
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:
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