2. a) Calculate the hard-sphere (HS) collision theory rate constant ks for the reaction NO(g) + C₁₂(g) Þ NOCl(g) + HS Cl(g) at 300 K in units of dm³ mols. The collision diameters of NO and Cl₂ are 370 and 540 pm, respectively. 16.0 g/mol, and mcı Use masses of m₁ = 14.0 g/mol, mo = 35.0 g/mol. N = b) Now include the line-of-centers (LOC) energy criterion to find koc in units of dm³ mol¹ s¹ using E₁ = 84.9 kJ mol LOC LOC c) Calculate the ratio of kчs and kLoc to the experimental rate constant at 300 K given A = 3.981 10° dm³ mol¹ s and E₁ = 84.9 kJ mol‍¹. a -1

The rate of photodecomposition of the herbicide piclo- ram in aqueous systems was determined by exposure to sunlight for a number of days. One such experiment produced the following results. (Data from R.T. Hedlun and C.R. Youngson, “The Rates of Photodecomposition of Picloram in Aqueous Systems," Fate of Organic Pesticides in tbe Aquatic Environment, Advances in Chemistry Series, #111, American Chemical Society (1972), 159—172.) Exposure Time, t (days) [Pidoram] (mol L_1) 0 4.14 X 10-6 7 3.70 X 10-6 14 3.31 X 10-6 21 2.94 X 10~6 28 2.61 X 10~6 35 2.30 X 10-6 42 2.05 X 10-6 49 1.82 X 10"6 56 1.65 X 10-6 Determine the order of reaction, the rate constant, and the half-life for the photodecomposition of picloram.

(a) Distinguish between reactions rate and reaction mechanism (b) The following data were obtained for the reaction I'aq + OCI aq→ IO" + CI'aq [OCI ] [1] mol/dm3 Initial Rate mol/dm3 mol/dm?/s 1.8 x 103 3.6 х 103 2.1 x 103 5.4 x 105 2.1 x 103 10.8 x 10$ I II I 1.8х 103 (i)What is the order of the reaction with respect to [I'] and [OCI] (ii) Calculate the rate constant using the results of experiment II (iii) What is the rate law or rate equation for this reaction? 6.3х 103 4.9 x 104

(a) Explain the meaning of the sentence:“The velocity laws of reactions are empirical” (b) It can be determined that the velocity law of a generic reaction A +B→Pév = k[A]x[B]y. Plot on a graph the variation of [A] and [P] with time, and explain why v= d[P]/dt = -d[A]/dt. (c) Explain the meaning of the terms k, x and y, in the velocity law, presented in item b: (d) Explain what it means in practice for a velocity law to be of zero order. Plot ,A as a function of t, for the zero-order reaction A→Products. (e) Explain what elementary reactions are and how they can be classified.

In a study of the gas phase decomposition of hydrogen iodide at 700 K HI(g)- → H₂(g) + ½ I₂(g) the concentration of HI was followed as a function of time. It was found that a graph of 1/[HI] versus time in seconds gave a straight line with a slope of 1.64×10-³ M-¹ s-¹ and a y-intercept of 0.418 M-¹. Based on this plot, the reaction is order in HI and the rate constant for the reaction is M-¹ S-¹.

In a study of the gas phase decomposition of nitrosyl chloride at 400 K NOC(gNO(g) + ½ Cl2(g) the concentration of NOCI was followed as a function of time. It was found that a graph of 1/[NOCI] versus time in seconds gave a straight line with a slope of 7.97x10-4 M sl and a y-intercept of 38.0 M!. Based on this plot, the reaction is | order in NOCI and the rate constant for the reaction is

Obtain the 2"-1 – 1 | T (п - 1)k. а"-1 relation between the order of the reaction (n), the reaction rate constant (k), the initial concentration (a), and the half-life (T).

In a study of the decomposition of nitrous oxide at 565 °CN2O(g)N2(g) + ½ O2(g)the concentration of N2O was followed as a function of time.It was found that a graph of 1/[N2O] versus time in seconds gave a straight line with a slope of 1.55×10-3 M-1 s-1 and a y-intercept of 0.952 M-1.Based on this plot, the reaction is     order in N2O and the rate constant for the reaction is M-1 s-1.

The Arrhenius parameters for the gas-phase decomposit ion of cyclobutane, C4H8(g)→ 2 C2H4(g). are log(A/s-1) = 15.6 and Ea = 261 kJ mol- 1. What is the ha lf- life of cyclobutane at (a) 20 °C, (b) 500 °C?

The rate law for the reaction A + 3B → 2C + D was found to be v = k[A]2[B]2. (a) What are the units of k? (b) Express the rate law in terms of the rates of formation and consumption of A and C, respectively.