Q2.some PH3(9) is introduced into a flask at 600c containing an insert gas. PH3 proceeds to decomposed into P4 (9) & H2(9) & rxn. gas to completion. Total pressure is given below as function of time. Find order of rxn. & calculate rate constant.
p(mmhg 262.4 272.9 279.51 276.4
ans:- 4pH3(9)+ inertgasp4(9)+ 6H2(9) + inert gas
at t=0
t=60
t=120
t=
also at t=0, p+p'=276.4----------(2)
p=18.66mm &p'=243.74mm
at t=60, pressure=272=(p-a)+p'+a/4+6a/4
272.9=18.66-A+243.74+7A/4
=A=14mm
at t=120, pressure 272.51=p-A'+p'+A'/4+6A'/4
275.51=18.66-a'+243.74+7A'/4
A'=17.48mm
rxn is ist order
in process it contains bnth to b(n+2) & B(n+4) t0 b(n-1)
vol of reactant consumed is 25ml & at t=10min, vol used is 32 ml.
calculate rate constant for conversion of Bn+ of B(n+4)
assuming it to be a ist order
Ans:- bn+B(n+4)
a 0
(a-x) x
Bn+B(n+2)++2e- nfactor
= 2 B(n+4)++5e-B(n-1)+nfactor=5
Let normality be n for reducing agent so, at t=0 ax2= Nx25(by law of equivalence)
at t=t,(a-x)x2+5.x=nx32-------(11) for Bn+
for B(n+4)xfrom (i)
and (ii)
2.07x10-2min-1
____________Intentanious rate
average rate
order of reaction
Rate of reaction
Rate constant
Law of mass action
Molecularity of rxn.
Machanism of rxn.
Half life
Initial rate method
Preuodo Ist order rxn.
Inversion of regur
Activation energy
Collision frequency
Arrhenins Eq.
Transition state
Q.4: [Concept of sequential reaction:]
The reactant A with ini9tial concentration A goes to B. B instantly starts forming
at a different rate. Find the time at which max conc. Of B occurs and this concentration?
Given k1 and k2
sol :-
Rate laws:
Dumb question:
why is
sol:- b forms at a rate of k,a it instanteously goes to c with arate k2
p4(9)+ 6H2(9) + inert gas 
rxn is ist order
