Order Chemical Kinetics and Solid State Assignment

Order Chemical Kinetics and Solid State Assignment
1. Decomposition of NH3
gas on heated tungsten surface gave the following data. Calculate the order and the mean value
of the rate constant.
initial pressure po
(in mm Hg) 65 105 150 185
T1/2 (sec) 290 460 670 820
2. Decomposition of N2
O(g) conforms to , order kinetics. The rate constant gets quadrupled over the temperature range
298 K to 308 K. Calculate an approximate value of the activation energy, Ea
. Further, assuming constancy of activation
energy calculate the temperature at which, the rate constant again gets quadrupled.
3. A first order reaction is 30% complete in one hour. How much more time will elapse to reach the stage when 30% of
the initial concentration will remain?
4. For the reaction, A(g) o 2 B(g) C(g) at 100qC, , order kinetics is observed starting with pure A, the total pressure after
10 minutes is 176 mm. After a long time, the total pressure had the limiting value of 270 mm. Calculate an approximate
value of the rate constant.
5. The rate of a chemical reaction increases two times for every 20qC rise of temperature. If the rate constant at 30qC is
‘K’ what is the value of rate constant at90qC?
6. Metallic lead crystallizes in the fcc system. The side length of the unit cell = 4.92 Å. Atomic weight of lead = 207.2 g.
Calculate the density. N0
= 6.02 u 1023 mol–1.
Order Chemical Kinetics and Solid State Assignment
7. (a) In an fcc lattice of atoms what is the number of nearest neighbours and next nearest neighbours for each atom.
(b) In an fcc lattice of anions what is the cation–anion radius ratio, r
¨ ¸ © ¹ if the cation is of the right size, just to fit
the octahedral hole.
8. Cs, lattice consists of two interpenetrating simple cubic lattices side length of the unit cell = 4.562 Å. Calculate density.
At. wt of Cs = 133, , = 127.
9. Silver (at. wt = 107.88 g) crystallizes in the fcc system density = 10.53 g/cm3
= 6.02 x 1023. Calculate the side length of the unit cell.
10. (i) Barium titanate has the perovskite structure i.e., cubic with Ba2 ions at the corners, O2–ions at the face centers Ti 4
at the centre of the unit cell. If Ti 4 ion is taken to occupy voids (or holes) in the oxide lattice, what type of void
is occupied?
(ii) Metallic gold crystallizes in the fcc lattice. Side length a, of the unit cell = 4.07 Å. What is the closest distance
between the atoms of gold