Acompound decomposes by a first-order process. if 26 of the compound decomposes in 60 minutes, the half-life of the compound is .

(a) 26
(b) 31
(c) 18
(d) 5
(e) 138

(E) 138

Explanation:

Using integrated rate law for first order kinetics as:

Where,  

is the concentration at time t

is the initial concentration

Given:

26 % is decomposed which means that 0.26 of is decomposed. So,

= 1 - 0.26 = 0.74

t = 60 min

Taking natural log both sides, we get that:-

k = 0.005018 min⁻¹

Also,  Half life expression for first order:-

Where, k is rate constant

So,  

The correct option is:- (E) 138

answer: semi-infinite solid initially at a uniform temperature of 400 ◦c is cooled at its surface by convection. the cooling fluid at a constant temperature of 200 ◦c has a convective coefficient (ha) of 250 w/m2.k. the physical properties of the solid: k = 20 w/m.k and α = 4 * 10-5  m2/s. using δx = 0.04 m and δt = 10 s. write the finite difference equations describing the transient heat transfer of the first five δx and the temperature profile after 30 s.