# Chemical Reaction Engineering GATE-2013

**Q 1:** The exit age distribution for a reactor is given by E(t) = δ(t – 4), where t is in seconds. A first-order liquid phase reaction (k = 0.25 s^{-1}) is carried out in this reactor under steady state and isothermal conditions. The mean conversion of the reactant at the exit of the reactor, up to 2 digits after the decimal point, is ______.

**Q 2:** An isothermal liquid phase zero order reaction A → B (k = 0.5 mol/m^{3}-s) is carried out in a batch reactor. The initial concentration of A is 2 mol/m^{3}. At 3 seconds from the start of the reaction, the concentration of A in mol/m^{3} is __________.

**Q 3:** The overall rates of an isothermal catalytic reaction using spherical catalyst particles of diameters 1 mm and 2 mm are r_{A1} and r_{A2} (in mol (kg-catalyst)^{-1} h^{-1}), respectively. The other physical properties of the catalyst particles are identical. If pore diffusion resistance is very high, the ratio r_{A2}/r_{A1} is __________.

**Q 4:** The gas phase decomposition of azomethane to give ethane and nitrogen takes place according to the following sequence of elementary reactions.

Using the pseudo-steady-state-approximation for [(CH_{3})_{2}N_{2}]*, the order with respect to azomethane in the rate expression for the formation of ethane, in the limit of high concentrations of azomethane, is ___________.

**Q 5:** A first-order liquid phase reaction is carried out isothermally at a steady state in a CSTR and 90 % conversion is attained. With the same inlet conditions and for the same overall conversion, if the CSTR is replaced by two smaller and identical isothermal CSTRs in series, the % reduction in total volume, to the nearest integer, is __________.

###### Common data for Q 6 & 7:

Liquid reactant A decomposes as follows

A\rightarrow R\;\;r_R=k_1C_A^2\;\;\;k_1=0.5m^3/mol‐s A\rightarrow S\;\;r_S=k_2C_A\;\;k_2=1s^{-1}An aqueous feed of composition C_{A0} = 30 mol/m^{3}, C_{R0} = 2 mol/m_{3}, and C_{S0}= 1 mol/m^{3} enters a CSTR in which the above reactions occur. Assume isothermal and steady-state conditions.

**Q 6:** If the conversion of A is 80 %, the concentration of R in the exit stream in mol/m^{3}, to the nearest integer, is _________.

**Q 7:** What is the % conversion of A, to the nearest integer, so that the concentration of S in the exit stream is 11.8 mol/m^{3}? _________