(a)
Interpretation:
The half-lives of decomposition of
Concept Introduction:
The half-life of the particular
(b)
Interpretation:
The time taken by
Concept Introduction:
According to the integrated rate law for the first order reaction, the concentration of reactant is the exponential function of time. The two equations that represent the integrated rate law for the first order kinetics is shown below.
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Chemical Principles: The Quest for Insight
- (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.arrow_forwardThe degradation of the antibiotic clindamycin stored at 343 K in aqueous solution at pH 4 is found to be first order with a rate constant of 2.49 x 10−7 s −1. Over the temperature range 320 K to 360 K theactivation energy was found to be 123.3 kJ mol−1. (a) Calculate the rate constant at 325 K.(b) The threshold for product safety is 1% degradation. At 295 K the time taken for 1% of the antibiotic to degrade is found to be close to 0.01/ k. Comment on the shelf-life of the drug.arrow_forwardThe rate constant for the first-order decomposition of N2O5 in the reaction 2 N2O5(g) → 4 NO2(g) + O2(g) is kr = 3.38 × 10−5 s−1 at 25 °C. What is the half-life of N2O5? If the initial partial pressure of N2O5 is 500 Torr, what will its partial pressure be (i) 50 s, (ii) 20 min after initiation of the reaction?arrow_forward
- The isomerization reaction CH3NC → CH3CN obeys the first-order rate law, rate = k[CH3NC], in the presence of an excess of argon. Measurement at 500. K reveals that in 485 seconds, the concentration of CH3NC has decreased to 73% of its original value. Calculate the rate constant (k) of the reaction at 500. K. s−1 (The integrated form for the first-order rate law can be written in the general terms ln[A]t − ln[A]0 = −kt, where [A]0 is the initial concentration of reactant A, [A]t is the concentration of A at time t, and k is the rate constant.)arrow_forwardAssume that the formation of nitrogen dioxide: 2NO(g) + O2(g) 2NO2(g) is an elementary reaction. (a) Write the rate law for this reaction. (b) A sample of air at a certain temperature is contaminated with 2.0 ppm of NO by volume. Under these conditions, can the rate law be simplified? If so, write the simplified rate law. (c) Under the conditions described in part (b), the half-life of the reaction has been estimated to be 6.4 × 103 min. What would the half-life be if the initial concentration of NO were 10 ppm?arrow_forward20B.2(b) The rate constant for the first-order decomposition of a compound A in the reaction 2 A→P is krr=3.56×10−7 s−1 at 25 °C. What is the half-life of A? What will be the pressure, initially 33.0 kPa after (i) 50 s, (ii) 20 min after initiation of the reaction?arrow_forward
- The enzyme urease catalyzes the reaction of urea, 1NH2CONH22, with water to produce carbon dioxide and ammonia. In water, without the enzyme, the reaction proceeds with a first-order rate constant of 4.15 * 10-5 s-1 at 100 °C. In the presence of the enzyme in water, the reaction proceeds with a rate constant of 3.4 * 104 s-1 at 21 °C. (a) Write out the balanced equation for the reaction catalyzed by urease.arrow_forwardAcetone is one of the most important solvents in organicchemistry, used to dissolve everything from fats and waxes toairplane glue and nail polish. At high temperatures, it decom-poses in a first-order process to methane and ketene(CH2=C=O). At 600C, the rate constant is 8.7x10^-3s⁻¹.(a) What is the half-life of the reaction?(b) How long does it take for 40.% of a sample of acetone todecompose?(c) How long does it take for 90.% of a sample of acetone todecompose?arrow_forwardFor the reaction: 2N205(g) -->4NO(g) + O2(g) (a) write the mathematical rate expression in terms of (i) the disappearance of N2O5 (Reactant); (ii) the formation of NO (Product); (iii) the formation of O2 (Product). (b) What are the stoichiometric relationships (rationalization) of the various rates for this reaction? (e.g. Product C formation is 2x faster than Reactant A disappearance/decomposition.)arrow_forward
- 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.arrow_forward(iv) The activation energy, Ea, and pre-exponential factor, A, for the decomposition of N2O5: N2O5→ 2 NO2 + ½ O2 are: E = 102.2 kJ mol-1 and A = 2.81 x 1013 s-1. (a) Using these data calculate the rate constant of the reaction at 300 K. (b) Assuming the reaction is first order calculate the rate of the reaction, at 300 K, when the concentration of N2O5 is 0.015 mol L-1.arrow_forwardThe reaction between ethyl iodide and hydroxide ion inethanol (C2H5OH) solution, C2H5(1alc) + OH- (1alc)----->C2H5OH(l) + I - (alc) , has an activation energy of86.8 kJ>mol and a frequency factor of 2.10 x 1011 M-1 s-1.(a) Predict the rate constant for the reaction at 35 °C. (b) Asolution of KOH in ethanol is made up by dissolving 0.335g KOH in ethanol to form 250.0 mL of solution. Similarly,1.453 g of C2H5I is dissolved in ethanol to form 250.0mL of solution. Equal volumes of the two solutions aremixed. Assuming the reaction is first order in each reactant,what is the initial rate at 35 °C? (c) Which reagent inthe reaction is limiting, assuming the reaction proceeds tocompletion? (d) Assuming the frequency factor and activationenergy do not change as a function of temperature,calculate the rate constant for the reaction at 50 °C.arrow_forward
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