Question

1a) The decomposition of hydrogen peroxide is first order in [H2O2]. After 60 min the [H2O2] has fallen from 3.7 M to 3.4 M. The rate constant k, in min-1 , is A. 1.4 X 10-3 B. 6.1 X 10-4 C. 2.7 X 10-2 D. 8.3 X 10-3 E. 1.2 x 10-2

1b) What is the half-life, in seconds, of a first order reaction if 30% of the reactant has decomposed in 50 seconds? A. 50 B. 83 C. 26 D. 30 E. 97

Answer 1

we have the relation ta) for the first onder neaction; At = Ao ekt en At = ln Ao - kk kt = lnto - ln Az = In the fire Given: Ao =3.7M and At= 3.40 ; t= bomen ka rate constant = ? bomin 3.4m X 0.08456 1.4 x 10 min 1 bonum rate constant 16) K = 1 en Ao where Ao = 100% At = 100%-30% t= 50s = 70% ki še en 10 mm : 1 x 0.3567 = 0.007151 7ok Mary Life (+1) = 0.593 = 0.693. = 975. 0.00715!