(a)
Interpretation: The rate law reaction of decomposition of
Concept introduction: The change observed in the concentration of a reactant or a product per unit time is known as the rate of the particular reaction. The differential rate law provides the rate of a reaction at specific reaction concentrations.
To determine: The rate constant for
(b)
Interpretation: The rate law reaction of decomposition of
Concept introduction: The change observed in the concentration of a reactant or a product per unit time is known as the rate of the particular reaction. The differential rate law provides the rate of a reaction at specific reaction concentrations.
To determine: The time taken by
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Chemistry: An Atoms First Approach
- One experimental procedure that can be used to determine the rate law of a reaction is the method of initial rates. What data are gathered in the method of initial rates, and how are these data manipulated to determine k and the orders of the species in the rate law? Are the units for k. the rate constant, the same for all rate laws? Explain. If a reaction is first order in A, what happens to the rate if [A] is tripled? If the initial rate for a reaction increases by a factor of 16 when [A] is quadrupled, what is the order of n? If a reaction is third order in A and [A] is doubled, what happens to the initial rate? If a reaction is zero order, what effect does [A] have on the initial rate of a reaction?arrow_forwardThe Raschig reaction produces the industrially important reducing agent hydrazine, N2H4, from ammonia, NH3, and hypochlorite ion, OCl−, in basic aqueous solution. A proposed mechanism is Step 1: Step 2: Step 3: What is the overall stoichiometric equation? Which step is rate-limiting? What reaction intermediates are involved? What rate law is predicted by this mechanism?arrow_forwardIsomerization of CH3NC occurs slowly when CH3NC is heated. CH3NC(g) CH3CN(g) To study the rate of this reaction at 488 K, data on [CH3NC] were collected at various times. Analysis led to the following graph. (a) What is the rate law for this reaction? (b) What is the equation for the straight line in this graph? (c) Calculate the rate constant for this reaction. (d) How long does it take for half of the sample to isomerize? (e) What is the concentration of CH3NC after 1.0 104 s?arrow_forward
- At 573 K, gaseous NO2(g) decomposes, forming NO(g) and O2(g). If a vessel containing NO2(g) has an initial concentration of 1.9 102 mol/L, how long will it take for 75% of the NO2(g) to decompose? The decomposition of NO2(g) is second-order in the reactant and the rate constant for this reaction, at 573 K, is 1.1 L/mol s.arrow_forwardHydrogen peroxide, H2O2(aq), decomposes to H2O() and O2(g) in a reaction that is first-order in H2O2 and has a rate constant k = 1.06 103 min1 at a given temperature. (a) How long will it take for 15% of a sample of H2O2 to decompose? (b) How long will it take for 85% of the sample to decompose?arrow_forwardAt 500 K in the presence of a copper surface, ethanol decomposes according to the equation C2H5OH(g)CH3CHO(g)+H2(g) The pressure of C2H5OH was measured as a function of time and the following data were obtained: Time(s) PC2H5OH(torr) 0 250. 100. 237 200. 224 300. 211 400. 198 500. 185 Since the pressure of a gas is directly proportional to the concentration of gas, we can express the rate law for a gaseous reaction in terms of partial pressures. Using the above data, deduce the rate law, the integrated rate law, and the value of the rate constant, all in terms of pressure units in atm and time in seconds. Predict the pressure of C2H5OH after 900. s from the start of the reaction. (Hint: To determine the order of the reaction with respect to C2H5OH, compare how the pressure of C2H5OH decreases with each time listing.)arrow_forward
- The decomposition of iodoethane in the gas phase proceeds according to the following equation: C2H5I(g)C2H4(g)+HI(g) At 660. K, k = 7.2 104 sl; at 720. K, k = 1.7 102 sl. What is the value of the rate constant for this first-order decomposition at 325C? If the initial pressure of iodoethane is 894 torr at 245C, what is the pressure of iodoethane after three half-lives?arrow_forwardNitrosyl bromide, NOBr, is formed from NO and Br2: 2 NO(g) + Br2(g) 2 NOBr(g) Experiments show that this reaction is second-order in NO and first-order in Br2. (a) Write the rate equation for the reaction. (b) How does the initial reaction rate change if the concentration of Br2 is changed from 0.0022 mol/L to 0.0066 mol/L? (c) What is the change in the initial rate if the concentration of NO is changed from 0.0024 mol/L to 0.0012 mol/L?arrow_forwardThe reaction of CO(g) + NO2(g) is second-order in NO2 and zeroth-order in CO at temperatures less than 500 K. (a) Write the rate law for the reaction. (b) Determine how the reaction rate changes if the NO2 concentration is halved. (c) Determine how the reaction rate changes if the concentration of CO is doubled.arrow_forward
- Hydrogen iodide decomposes when heated, forming H2(g) and I2(g). The rate law for this reaction is [HI]/t = k[HI]2. At 443C, k = 30. L/mol min. If the initial HI(g) concentration is 1.5 102 mol/L, what concentration of HI(g) will remain after 10. minutes?arrow_forwardThe catalyzed decomposition of hydrogen peroxide is first-order in [H2O2]. It was found that the concentration of H2O2 decreased from 0.24 M to 0.060 M over a period of 282 minutes. What is the half-life of H2O2? What is the rate constant for this reaction? What is the initial rate of decomposition at the beginning of this experiment (when [H2O2] = 0.24 M)?arrow_forwardAn excellent way to make highly pure nickel metal for use in specialized steel alloys is to decompose Ni(CO)4 by heating it in a vacuum to slightly above room temperature. Ni(CO)4(g) Ni(s) + 4 CO(g) The reaction is proposed to occur in four steps, the first of which is Ni(CO)4(g) Ni(CO)3(g) + CO(g) Kinetic studies of this first-order decomposition reaction have been carried out between 47.3 C and 66.0 C to give the results in the table. (a) Determine the activation energy for this reaction. (b) Ni(CO)4 is formed by the reaction of nickel metal with carbon monoxide. Suppose that 2.05 g CO is combined with 0.125 g nickel metal. Determine the maximum mass (g) of Ni(CO)4 that can be formed. Replacement of CO by another molecule in Ni(CO)4 was studied in the nonaqueous solvents toluene and hexane to understand the general principles that govern the chemistry of such compounds. Ni(CO)4(g) + P(CH3)3 Ni(CO)3P(CH3)3 + CO A detailed study of the kinetics of the reaction led to the mechanism Step1:(slow)Ni(CO)4Ni(CO)3+COStep2:(fast)Ni(CO)3+P(CH3)3Ni(CO)3P(CH3)3 (c) Which step in the mechanism is unimolecular? Which is bimolecular? (d) Add the steps of the mechanism to show that the result is the balanced equation for the observed reaction. (e) Is there an intermediate in this reaction? If so, what is it? (f) It was found that doubling the concentration of Ni(CO)4 increased the reaction rate by a factor of 2. Doubling the concentration of P(CH3)3 had no effect on the reaction rate. Based on this information, write the rate equation for the reaction. (g) Does the experimental rate equation support the proposed mechanism? Why or why not?arrow_forward
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