For the first order consecutive reaction : Which of the following statement is incorrect ?
[B] is always greater than [C]
In a consecutive first-order scheme the intermediate B is formed from A and consumed to give C, so each species has a characteristic time profile. The question asks which description does not match.
"[B] is always greater than [C]" is the incorrect statement. B is an intermediate: it starts at zero, rises to a maximum, then falls back towards zero as it is converted onward. C is the final product: it starts at zero and rises monotonically towards the full initial amount of A. The two curves must therefore cross. At long times essentially all the material ends up as C while B has been consumed, so [C] greatly exceeds [B]. The claim holds only in the earliest part of the reaction, never "always".
"[A] decreases exponentially with time" is correct. A is consumed by a simple first-order step unaffected by anything downstream, so \([A] = [A]_0 e^{-k_1 t}\).
"[C] increases with an inverse exponential function" is correct in the sense meant — C follows a rising, saturating curve of the form \(1 - e^{-kt}\) terms, approaching \([A]_0\) asymptotically. Its curve is also sigmoidal at early times, showing an induction period while B accumulates.
"tmax depends on K1 and K2" is correct. Setting \(\frac{d[B]}{dt} = 0\) gives \(t_{max} = \frac{\ln(k_2/k_1)}{k_2 - k_1}\), which manifestly involves both rate constants.
Hence the incorrect statement is that [B] is always greater than [C].
Similar Questions
The property measured in derivative thermogravimetric analysis (DTG) is :
Analysis of four different samples of an alloy yielded 12.12, 12.14, 12.10 and 12.22% of metal. The mean deviation of the result is :
A given reaction is fitted into the following Arrhenius form :
K2 = 6.0 × 1014 (S-1) . exp \(\left[-\frac{104.4\ (\mathrm{kJ\,mol^{-1}})}{RT}\right]\)
Value of the rate constant at very high temperature would be :
The following half cell represents, normal hydrogen electrode (NHE) :
If, we discharge the electrochemical cell rapidly, then :
E° value for various ions are as follows :
E°(MnO4-) = +1.51 V
E°(Ag/Ag+) = +0.7996 V
E°(Au/Au+) = +1.692 V
E°(Zn/Zn2+) = -0.761 V
Based on this data, permaganate can be used to oxidize :
Vapour pressure of 0.5 molal solution of non-volatile solute in organic solvent at 30°C would be :
(Given : vapour pressure of pure organic solvent is 100 torr; the molecular weight of organic solvent is 100 g mol-1).
Molar conductance of 0.01 M acetic acid was found to be 16 × 10-4 S m2 mol-1 at 30°C. Molar conductance of H+ and CH3COO- ions at infinite dilution are 350 × 10-4 S m2 mol-1 and 50 × 10-4 S m2 mol-1, respectively at same temperature. What percentage of acetic acid is dissociated at that concentration ?
The variation of Cp with pressure at constant temperature is given by :
Consider the reaction :
H2S(g) + \(\tfrac{3}{2}\) O2(g) → SO2(g) + H2O(g), ΔH° = 518.62 kJ
What is the effect of increase of temperature and pressure on the reaction ?
Important Questions from Thermodynamics
Two blocks of ice when pressed together join to form one block because
The ratio C p/C vof the specific heats at constant pressure and volume of a monoatomic ideal gas in two dimensions is
The total number of phonon modes in a solid of volume V is \(\int_{\rm{0}}^{{\rm{ω_ D}}} {{\rm{g}}\left( {\rm{ω }} \right)\,} {\rm{dω }}\) = 3N, where N is the number of primitive cells, ω Dis the Debye frequency and density of photon modes is g( ω ) = AV ω2 (with A > 0 a constant). If the density of the solid doubles in a phase transition, the Debye temperature θ D, will
The dispersion relation of a gas of non-interacting bosons in d dimensions is E(k) = ak s, where a and s are positive constants. Bose-Einstein condensation will occur for all values of
Example of thermoplastic among the following is
