Question

(a) The decomposition of A into products has a value of K as 4.5x103 s-1 at 10 °C and A of activation 60 kJ mol-1. At what temperature would K be 1.5x104 51.

(b) i) If the half-life period of a first-order reaction is x and, 3/4th life period of the same reaction is y, how are x and y related to each other?
ii) In some cases it is found that a large number of colliding molecules have energy more than threshold energy, yet the reaction is slow. Why?

Answer 1

Answer:

The decomposition of A into product has value of k as 4.5 x 103 s-1 at 10°C and energy of activation 60 kJ mol-1. At what temperature would k be 1.5 x 104 s-1? Hence, k would be 1.5 × 104 s - 1 at 24°C.

Answer 2

Answer:

k would be 1.5 × 104 s - 1 at 24°C.

Explanation:

a) From Arrhenius equation, we obtain

log k2/k1 = Ea / 2.303 R (T2 - T1) / T1T2

Also, k1 = 4.5 × 103 s - 1

T1 = 273 + 10 = 283 K

k2 = 1.5 × 104 s - 1

Ea = 60 kJ mol - 1 = 6.0 × 104 J mol - 1

Then,

log 1.5 X 10*4 / 4.5 X 10*3  = 6.0 x 10*4 Jmol*-1 / 2.303 x 8.314 J K *-1 mol*-1

0.5229 = 3133.627 [T2 - 283 / 283T2]

0.5229 x 283 T2 / 3133.627 = T2 - 283

= 0.472T2 = T2 - 283

= 0.9528 T2 = 283

= T2 = 297.019 K ( approximately )

= 297 K = 24 * C