Question

A B and C

Consider reaction iodide ion at 273 C. the of proxy bisulfate ion (s_2O_s^2) with iodide ion at 273 degree C. S_2O_s^3 (aq) + 3I (aq) rightarrow 2 SO_4^2(aq) + I_s(aq) What is the rate law for the reaction? Solve for the rate constant including units rate What is the activation energy of this reaction in kJ/mol?

Answer 1

rate kIS2Os] [I"where m and n are the orders with respect to peroxydisulfate and iodide, respective to determine the order with respect to peroxydisulfate, we look at experiments 1 and 2: the iodide concentration is constant, and the concentration of peroxydisulfate changes by a factor of 0.027M/0.018 M- 1.5 (the iodide concentration is fixed), and the rate changes by a factor (3.9 x10^-6 M/sec ) / ( 2.6 x10^-6 M/sec)-1.5 determine that the order with respect to peroxydisulfate is 1 (an increase the concentration by a factor of 1.5 results in an increase in the rate by a factor of 1.5), so the rate law (so far) is rate-k[S:082] [1.1° now, we must calculate the order with respect to iodide ion. looking at the experimental data, we see that there aren't two experiments where the peroxydisulfate concentration is held constant and the iodide concentration is varied. this is merely a minor inconvenience; it means that we shall have to write out the rate laws in their full form. above, we determined that the order with respect to peroxydisulfate =1; here, we will compare expts. 1 and 3. we write the rate law for expt. 3 and divide it by the rate law for expt. 1: Rate1 k[S2Os2][I]" substituting the data for experiments 1 and 3, (7.8 x10^-6 M/sec ) / ( 2.6 x 10^-6 M/sec)-k(0.036 M) (0.054 M)^n / k(0.018 M) (0.036 M)An now, do the divisions on the left and right hand sides. the rate constants will cancel since the temperature doesn't change during the reaction. we obtaindivide by 2:the only value of n that makes this true is n-1, so the order with respect to iodide ion 1, and the rate law is: rate k[S20s21[] -6 M K 1-4.01x10^-3 1/Msec K 2-4.01 x10A-3 1/Msec K 3-4.01 x10A-3 1/Msec K 4 3.89 x10A-3 1/Msec 2.6-10 3.9.10 7.8-10 1.4.10 sec sec k1-(0.018M)-(0036-MI) sec sec (0027 M 0.036MX3 (0036- (0054.M) 4(0050 M (0.072 M) looks like the average rate constant 4.0x 103 1/M sec