I. For the reaction given below, what is the instantaneous rate for each of the
ID: 567676 • Letter: I
Question
I. For the reaction given below, what is the instantaneous rate for each of the reactants and products? 3A + 2B 4C 2. Given the following experimental data, find the rate law and the rate constant for the reaction: NO (g) + NO2 (g) +O2(g) N2O5 (g) Run NOlo, M [N020, M [O2lo, M Initial Rate, Ms 1 0.10 M 0.10 M 2 0.20 M 0.10 M 3 0.20 M 0.30 M 4 0.10 M 0.10 M 0.10 M 2.1 x 10 0.10 M 4.2 x 102 0.20 M 0.20 M 1.26 x 10-1 2.1 x 102 3. The half-life of a radioisotope is found to be 4.55 minutes. If the decay follows first order kinetics, what percentage of isotope will remain after 2.00 hours?Explanation / Answer
3)
Given
Half life = 4.55 minutes = t1/2
for first order k = 0.693 / t1/2 = 0.693 / 4.55 min = 0.1523 min-1
Time t = 2 hrs = 120 min
for first order rate law - dC/dt = k C ; - dC/C = kt ; integrating from Co to C and 0 to t - ln (C/Co) = k (t-0)
C = Co e^(-kt) or
- ln(C/Co) = kt
-;ln ( C/Co) = 0.1523 min-1 * 120 min
- ln (C/Co) = 18.28
C/Co = e^(-18.28) = 1.155 * 10-8
percentage of isotope remaining = 1.155 * 10-8 * 100 % = 1.155 * 10-6 % Answer