Short Answer TypeA reaction is second order in A and first order in B.
(i) Write the differential rate equation.
(ii) How is the rate affected on increasing the concentration of A three times?
(iii) How is the rate affected when the concentrations of both A and B are doubled?
A first order reaction takes 40 minutes for 30% decomposition. Calculate t1/2 for this reaction.
(Given log 1.428 = 0.1548)
For a first order reaction, show that time required for 99% completion is twice the time required for the completion of 90% of reaction.
Give reasons for the following:
(i) Bond enthalpy of F2 is lower than that of Cl2.
(ii) PH3 has lower boiling point than NH3Account for the following:
(i) Helium is used in diving apparatus.
(ii) Fluorine does not exhibit positive oxidation state.
(iii) Oxygen shows catenation behaviour less than sulphur
(i) Helium mixed with oxygen under pressure is given to sea-divers for respiration. However, pure oxygen can be toxic at great concentrations at the depth. Therefore oxygen can be mixed with helium to reduce oxygen concentration while eliminating nitrogen. During controlled decompression, the helium would also diffuse out of tissue and the lungs are more easily than nitrogen avoiding the bends .Use of helium for relatively shallow scuba diving would likely permit longer driving times with less threat of the bends.
(ii) Fluorine being the most electronegative atom does not exhibit positive oxidation state because the electrons in fluorine are strongly attracted by the nuclear charge because of the small size of a fluorine atom and therefore, removal of an electron is not possible.
(iii) Sulphur shows catenation behaviour more than that of oxygen because the oxygen atom is smaller in size as compared to sulphur, the O-O bonds in oxygen experiences repulsions due to the lone pairs present on oxygen atom and therefore, are weaker as compared to the S-S bonds.
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