QUESTION 1 a) Define rate of reaction. Write the expression to show the relationship between the rate of disappearance of mercury(II) chloride, HgCl2 and the rate of formation of mercury(1) chloride, Hg2Cl2. 2HgCl2 (aq) + C2042- (aq) → 2CI-(aq) + 2CO2 (g) + Hg2Cl2 (s) b) Calculate the activation energy, Ea (in J mol-1) of a reaction occurring at 679 K given that the forward reaction has a rate constant, k of 7.8 s-1 and Arrhenius constant, A of 16.3 s-1. State the effect on the Ea value when temperature is increased. The gas constant, R is 8.314 J mol-1 K-1.

QUESTION 1 a) Define rate of reaction. Write the expression to show the relationship between the rate of disappearance of mercury(II) chloride, HgCl2 and the rate of formation of mercury(1) chloride, Hg2Cl2. 2HgCl2 (aq) + C2042- (aq) → 2CI-(aq) + 2CO2 (g) + Hg2Cl2 (s) b) Calculate the activation energy, Ea (in J mol-1) of a reaction occurring at 679 K given that the forward reaction has a rate constant, k of 7.8 s-1 and Arrhenius constant, A of 16.3 s-1. State the effect on the Ea value when temperature is increased. The gas constant, R is 8.314 J mol-1 K-1.

Chemistry for Engineering Students

3rd Edition

ISBN:9781285199023

Author:Lawrence S. Brown, Tom Holme

Publisher:Lawrence S. Brown, Tom Holme

Chapter11: Chemical Kinetics

Section: Chapter Questions

Problem 11.52PAE

See similar textbooks

Similar questions

Express the rate of the reaction 2N2O(g)2N2(g)+O2(g) in terms of (b) [ N2O ] (a) [ O2 ]
11.41 For a drug to be effective in treating an illness, its levels in the bloodstream must be maintained for a period of time. One way to measure the level of a drug in the body is to measure its rate of appearance in the urine. The rate of excretion of penicillin is first order, with a half-life of about 30 min. If a person receives an injection of 25 mg of penicillin at t = 0, how much penicillin remains in the body after 3 hours?
What is the difference between average rate, initial rate, and instantaneous rate?
A study of the rate of the reaction represented as 2AB gave the following data: Time (s) 0.0 5.0 10.0 15.0 20.0 25.0 35.0 [A](M) 1.00 0.775 0.625 0.465 0.350 0.205 0.230 (a) Determine the average rate of disappearance of A between 0.0 s and 10.0 s, and between 10.0 s and 20.0 s. (b) Estimate the instantaneous rate of disappearance of A at 15.0 s from a graph of time versus [A]. What are theunits of this rate? (c) Use the rates found in parts (a) and (b) to determine the average rate of formation of B between 0.00 s and 10.0 s, and the instantaneous rate of formation of B at 15.0 s.
Nitrosyl chloride (NOCI) decomposes to nitrogen oxide and chlorine gases. (a) Write a balanced equation using smallest whole-number coefficients for the decomposition. (b) Write an expression for the reaction rate in terms of [NOCl]. (c) The concentration of NOCl drops from 0.580 M to 0.238 M in 8.00 min. Calculate the average rate of reaction over this time interval.
11.64 HBr is oxidized in the following reaction: 4 HBr(g) + O2(g) —• 2 H2O(g) + 2 Br,(g) A proposed mechanism is HBr + O2 -* HOOBr (slow) HOOBr + HBr — 2 HOBr (fast) HOBr + HBr — H2O + Bn (fast) Show that this mechanism can account for the correct stoichiometry. Identify all intermediates in this mechanism. What is the molecularity of each elementary’ step? Write the rate expression for each elementary' step. Identify the rate-determining step.
The rate of the decomposition of hydrogen peroxide, H2O2, depends on the concentration of iodide ion present. The rate of decomposition was measured at constant temperature and pressure for various concentrations of H2O2and of KI. The data appear below. Determine the order of reaction for each substance, write the rate law, and evaluate the rate constant. Rate [H2OJ [Kll (mL min-’) (mol L ’) (mol L ’) 0.090 0.15 0.033 0.178 0.30 0.033 0.184 0.15 0.066
Make a graph of [A] versus time for zero-, first-, and second-order reactions. From these graphs, compare successive half-lives.
The initial rate for a reaction is equal to the slope of the tangent line at t 0 in a plot of [A] versus time. From calculus, initial rate = d[A]dt . Therefore. the differential rate law for a reaction is Rate = d[A]dt=k[A]n. Assuming you have some calculus in your background, derive the zero-, first-, and second-order integrated rate laws using the differential rate law.
The decomposition of gaseous dimethyl ether at ordinary pressures is first-order. Its half-life is 25.0 minutes at 500 C: CH3OCH3(g) CH4(g) + CO(g) + H2(g) (a) Starting with 8.00 g of dimethyl ether, what mass remains (in grams) after 125 minutes and after 145 minutes? (b) Calculate the time in minutes required to decrease 7.60 ng (nanograms) to 2.25 ng. (c) What fraction of the original dimethyl ether remains after 150 minutes?
For the reaction A+BC, explain at least two ways in which the rate law could be zero order in chemical A.
As with any drug, aspirin (acetylsalicylic acid) must remain in the bloodstream long enough to be effective. Assume that the removal of aspirin from the bloodstream into the urine is a lirst-order reaction, with a half-life of about 3 hours. The instructions on an aspirin bottle say to take 1 or 2 tablets every 4 hours. If a person takes 2 aspirin tablets, how much aspirin remains in the bloodstream when it is time for the second dose? (A standard tablet contains 325 mg of aspirin.)