Q13 of 26 Page 1

A first order reaction takes 10 minutes for 25% decomposition. Calculate t1/2 for the reaction.

[Given : log 2 =0.3010,log 3 = 0.4771, log 4 = 0.6021]


Given:


Time (t) = 10 minutes


For a first order reaction


=


Also,



Where Ro = initial concentration and R is remaining concentration at time ‘t’


Let initial concentration of 100 mol/L


So, ATQ,


K=


= 0.2303


= 0.2303 × (0.6021-0.4771)


=0.029


=


=


= 23.89 minutes approximately.


More from this chapter

All 26 →
11

An element crystallizes in a structure having a fcc unit cell of an edge 200 pm. Calculate the density, if 200 g of this element contains 24 x 1023atoms.

 12

Calculate the emf of following cell at 298K

Mg (s) | Mg2+ (0.01 M) ||Ag+ (0.0001 M) l Ag (s)


(Given:E° Mg2+/Mg = -2.37V E° Ag+/Ag = +0.80V)


OR


The conductivity of 0.001 mol/L solution of CH3COOH is 4.95 x 10-5 S cm-1. Calculate its molar conductivity and degree of dissociation (α). Given: λ°H+ = 349.6 S cm2/mol and λ°CH3COO- = 40.9 S cm2/mol


 14

Define the following:

(a) Brownian Movement


(b) Multimolecular Colloids


(c) Homogeneous Catalysts


 15

Give reasons for the following:

(a) Zinc and not copper is used for the recovery of metallic silver from complex [Ag(CN)2] .


(b) Alumina is dissolved in cryolite for electrolysis instead of being electrolysed directly.


(c) Zinc oxide can be reduced to metal by heating with carbon but not Cr2O3.