Chemical kinetics Questions and Answers

9 The three step mechanism for the following reaction can be seen below 2A 2B C 2D Step 1 2B G E Step 2 F A D F Step 3 F AC D G Slow Fast Fast a Are there any intermediates in the reaction mechanism for this reaction If so what are they b Is there a catalyst in this reaction mechanism If so what is it c Does this reaction mechanism have a rate determining step If so which step is it

6 For the following reaction 4 experiments have been run and the data collected is in the following table 2 MnO ag 5 H C O aq 6 H aq 2 Mn aq 10 CO g 8 H 0 1 Experiment H M Rate M s 0 2690 0 1147 0 2270 0 2776 0 7420 0 4431 0 3840 0 1147 0 5610 0 3258 0 4910 0 2203 2 3 MnO M H C O4 M 0 3470 0 6210 4 5 0 2410 0 3260 0 5630 0 2410 0 4140 0 3260 a Find the order of the reaction with respect to H 0 5740 0 3470 0 5740 0 4930 b Find the order of the reaction with respect to MnO c Find the order of the reaction with respect to H C O4 d What is the overall order of the reaction e Write the rate expression Calculate the rate constant k Kinetics Dry Lab 3 g If the concentration of MnO H C O4 H are 0 155 M 0 293M and 0 475M respectively what is the rate of the reaction

hat mass of glycerin C3H8O3 a nonelectrolyte must be dissolved in 200 0 g water to give a solution with a freezing point of 0 500 C his problem requires values in your textbook s specific appendices which you can access through the OWLv2 MindTap Reader You should not use the OWLv2 eferences Tables to answer this question as the values will not match ass g

olution contains 3 25 g of a nonvolatile pure hydrocarbon in 95 g acetone The boiling points of pure acetone and the solution are 55 95 C and 56 50 C respectively The mol ling point constant of acetone is 1 71 C kg mol What is the molar mass of the hydrocarbon lar mass g mol

3 The decomposition of N O5 in the gas phase was studied at constant temperature 2N2O5 g 4NO2 g O2 g The following results were collected N O5 0 1000 0 0707 0 0500 0 0250 0 0125 0 00625 Ln N O5 Time s 50 100 200 300 400 a Complete the table Using the data and graph paper plot the N O5 versus time and Ln N Os versus time Determine the value of k Which graph did you use b On your graph of N O5 versus time highlight the times it takes for each halving of the reactant concentration What is the half life Using this half life calculate k

1 Using the following chemical equation and data Experiment 1 2 3 4 3A B 2CD 2E Initial A 1 0 x 10 1 0 x 10 2 2 0 x 10 2 2 0 x 10 2 Initial B 4 0 x 10 3 8 0 x 10 3 8 0 x 10 3 8 0 x 10 3 Initial C 2 0 x 102 2 0 x 10 2 2 0 x 10 2 1 0 x 10 Initial Rate 5 mM s 10 mM s 40 mM s 40 mM s a Determine the rate equation b Calculate the specific rate constant k c Determine the initial rate of reaction if the initial concentrations of A B C are 3 x 10 2 M 5 x 10 M 5 x 10 5 M respectively for the reaction

4 Using the Arrhenius equation one can design experiments to find the activation energy Ea k Ae Ea RT or by setting up this equation to find Ea k k k s 2 0 x 10 5 In 7 3 x 10 5 2 7 x 10 4 9 1 x 10 4 2 9 x 10 3 Using the following data for the N O5 decomposition calculate the average E using at least 3 values of Ea to find the average and standard deviation Ea Note the value of R is 8 3144 J K mol 12 T C 20 30 40 50 60 T K

2 The reaction between bromate ions and bromide ions in acidic aqueous solution is given by the following equation BrO aq 5Br aq 6H aq 3Br2 1 3H O 1 The experimental results are given below Using these data determine the orders for all reactants the overall reaction order and the value of the rate constant Experiment 1 2 3 4 Initial BrO 0 10 0 20 0 20 0 10 Initial Br 0 10 0 10 0 20 0 10 Initial 0 10 0 10 0 10 0 20 Initial Rate MS 8 0 x 104 1 6 x 10 3 3 2 x 10 3 3 2 x 10 3

The mechanism proposed for the oxidation of iodide ion I by the hypochlorite ion CIO in aqueous solution is shown fast in both directions 1 ClO aq H O l HCIO aq OH aq 2 I aq HCIO aq HIO aq Cl aq 3 HIO aq OH aq IO aq H O l Complete the rate law for the formation of IO implied by this mechanism rate k slow fast OH Answer Bank HIO H O Fran 10 JOI

How are the following aspects of a reaction affected by the addition of a catalyst Increased activation energy of the reverse reaction rate of the reverse reaction Decreased the overall reaction AH Answer Bank activation energy of the forward reaction What other aspects of a catalyzed reaction are different from the uncatalyzed reaction Not affected rate of the forward reaction

The presence of a catalyst provides a reaction pathway in which the activation energy of a reaction is reduced by 48 00 kJ mol Uncatalyzed Catalyzed Determine the factor by which the catalyzed reaction is faster than the uncatalyzed reaction at 289 0 K if all other factors are equal kcat Kuncat A B E 130 00 kJ mol AB E 82 00 kJ mol Keat times faster Determine the factor by which the catalyzed reaction is faster than the uncatalyzed reaction at 353 0 K if all other factors are equal times faster

Calculate the rate constant k for a reaction at 54 0 C that has an activation energy of 81 8 kJ mol and a frequency factor of 1 05 x 10 1 s 1 S

2 Technecium 99m is the most widely used isotope for medical applications It has a half life of 6 02 hours If 14 grams of Tc 99m are injected into the body how many grams will be left undecayed after 24 08 hours

6 In the 1970s and 1980s East German Secret Police Stasi used scandium 46 to track suspected dissidents Sc 46 has a half life of 83 79 days How many days would it take for only 1 8 of a sample to remain undecayed on a suspect

Using photoelectron spectroscopy the ionization energy of the least tightly bound valence electron on F was determined to be 17 4 eV Calculate the Zeffective for this electron

yone Sot as a whole 2 How many half lives would it take for 2400 atoms to decay into 75 atoms show your work

5 Cesium 137 is also harmful byproduct of nuclear fission It is the principal source of radiation in the zone of alienation around the Chernobyl nuclear power plant How long is its half life if 25 grams of a 100 gram sample remains undecayed after 60 34 years

3 Cigarette smoke contains Polonium 210 which has a half life of 138 376 days What fraction of the original amount of Po 210 remains undecayed after 415 13 days

23 Fission and fusion are two types of nuclear reactions that change the atoms in the reactants and release large amounts of energy although they do so in different ways Which of the following statements describing nuclear reactions is true for both fission and fusion reactions A The combined mass number of the products is less than the combined mass number of the reactants B The reactions consist of the nucleus of a large atom splitting to form two smaller atomic nuclei C The reactions consist of the nuclei of two smaller atoms combining to form one larger atomic nucleus D The atomic numbers of the product elements are different than the atomic numbers of the reactants

8 Predict the missing product in the acid base reaction A HNa B CIOH C NaCl CO D A HCI NaOH 9 The temperature of a 100 mL sample of pure water is 25 C This is a measure c the amount of chemical energy stored in the water molecules the amount of heat released when water molecules react C the average kinetic energy of the water molecules D the total potential energy of the water molecules B H O

Methane gas CH4 reacts with oxygen gas O according to the equation below CH4 20 CO H O energy This reaction releases 890 kJ of energy for every mole of methane consumed Part 1 Is this reaction endothermic or exothermic Part 2 What is the enthalpy change value for this reaction Part 3 Explain in terms of potential energy which has more energy the products or the reactants Explain your response

Suppose experiments show that if the chemical reaction N 05 2NO 0 takes place at a certain temperature the rate of reaction of dinitrogen pentoxide is proportional to its concentration as follows d N 05 dt B 0 0007 N 05 a Find an expression for the concentration N O5 after t seconds if the initial concentration is C b How many seconds will the reaction take to reduce the chacentration of N O5 to 90 of its original value Round your answer to one decimal place

The rate constant for this first order reaction is 0 0740 s at 400 C A products After how many seconds will 20 3 of the reactant remain

For A products time and concentration data were collected and plotted as shown A M t s 0 600 00 0 0 484 30 0 0 405 60 0 0 349 90 0 t Determine the reaction order the rate constant and the units of the rate constant order A In A 1 A

O A About 46 weeks OB About 51 weeks Oc About 76 weeks OD About 40 weeks

The reaction A B C D rate k A B has an initial rate of 0 0430 M s What will the initial rate be if A is halved and B is tripled initial rate What will the initial rate be if A is tripled and B is halved

identify what the graphs of X versus time and Y versus time would look like for various orders In each graph represen either X or Y Zero order X versus t Zero order Y versus t First or second order X versus t Answer Bank First or second order Y versus t

The rate constant for this zero order reaction is 0 0340 M s at 300 C A products How long in seconds would it take for the concentration of A to decrease from 0 760 M to 0 340 M

The decomposition of N O can be described by the equation 2N O soln 4 NO soln O g Consider the data in the table for the reaction at 45 C in carbon tetrachloride solution z 8 0 125 526 735 average rate of reaction N 0 M average rate of reaction 2 542 2 350 Given the data calculate the average rate of reaction for each successive time interval What is the average rate of reaction for the time interval from 0 s to 125 s average rate of reaction 1 826 1 601 What is the average rate of reaction for the time interval from 125 s to 526 s What is the average rate of reaction for the time interval from 526 s to 735 s

The rate of the given reaction is 0 300 M s A 4B What is the relative rate of change of each species in the reaction A A At A B At A C 2C

DATA Cycle Initial Volumes 1 2 3 4 5 6 7 8 9 ANALYSIS Volume Beaker A mL 650 550 450 400 350 350 300 300 250 250 Volume Beaker B mL 0 100 200 250 300 300 350 350 400 400 Cycle 10 11 12 13 14 15 16 17 18 19 Volume Beaker A mL 1 Chemical equilibrium is defined as a dynamic state where the concentrations of the reactants and products remain constant over time as long as the conditions are not changed Explain how this 250 200 200 200 200 200 200 200 200 200 Volume Beaker B mL 400 400 450 450 450 450 450 450 450 450

WS 4 Rate Law and Reaction Mechanism 1 A reaction has the experimental rate law rate k A a 2 A reaction a How will the rate change if the concentration of A is tripled The rate would be 4 times Putter b How will the rate change if the concentration of A is halved The rate would decrease It would be a has the experimental rate law rate k A How will the rate change if the concentration of A is tripled fourth of the Briginal rate The rate would be 3 times faster b How will the rate change if the concentration of A is halved The rate woult decrease It would be one half 3 Write the rate law for the reaction C D CD that is third order in C and zero order in D Of the original 4 Give the following reaction and data answer the following questions 2 CIO 2T 2 C10 1 2 3 Experiment 1 C10 1 0 30 0 90 0 30 I 0 40 0 40 0 80 rate of disappearance of I 3 350 x 104 M s 9 045 x 10 M s 5 600 x 10 M s a What is the order with respect to ClO in this reaction b What is the order with respect to I in this reaction c What is the overall order in this reaction d Write the rate law for this reaction e Calculate the rate constant and include units f How does the rate of disappearance of I compare to the rate of appearance of 1

Biomed Anal 53 2010 376 81 Stability testing is a crucial step in the development of drugs The conditions and time that a drug will maintain its properties can impact its storage and shelf life as well as dosing of the drug Bupropion is the fourth most prescribed antidepressant however there are known issues with its stability To gain more information about its overall stability researchers have conducted studies to measure the stability of bupropion at different temperatures and pH s bupropion 1 Three different plots of the decomposition of 1 M bupropion over time at pH 11 and 30 C are shown below 16 bupropion m 0 8 0 6 0 4 0 2 0 0 50 0 5021 50 100 0 2521 100 Time hrs 150 200 In bupropion 0 0 5 1 5 2 2 5 3 0 50 0 689 50 Name 100 1 378 100 Time hrs 150 200 1 bupropion 1 M 12 a From the graphs above what is the reaction order circle zero order b Use the data above to determine the value of the rate constant including UNITS 0 0 100 3 967 50 1 992 50 first order 100 Time hrs HN 150 CH 200 second order c What will the concentration of bupropion be after 100 hours if the initial bupropion concentration is 2 5 M

3 The researchers also measured the rate constant for the decomposition of bupropion at several temperatures The data was used to create the Arrhenius plot shown at right What is the activation energy Ea in kJ mol In k 1 5 2 2 5 3 3 5 4 5 0 0029 y 6356 7x 16 695 Units for slope Kelvin 0 003 0 0031 0 0032 0 0033

Based on the graph what is the half life of iodine 131 O 8 days O 50 days O 32 days 65 5 days Amount of isotope remaining 100 0 90 0 80 0 70 0 60 0 50 0 40 0 30 0 20 0 10 0 0 0 0 8 16 lodine 131 decay 24 32 Time days 40 48 56 64

below Complete parts a d 30 pts 61 aq BrO3 aq 6 H aq 3 12 aq Br aq 3 H O 1 a Assign an oxidation number to each atom in each substance write answers below the arrows b Which reactant is oxidized c The initial rate was measured for several sets of initial reactant concentrations Use this information to determine the rate law for the reaction Make sure to show your work NOTE There are three reactants Expt 1 2 3 4 M Rate Law 0 0020 0 0040 0 0020 0 0020 Order for I Compare expt and BrO3 M 0 0080 0 0080 0 0160 0 0080 Which reactant is reduced H M Rate M min 0 020 0 020 0 020 0 040 where I is varied while Order for BrO3 Compare expt and where BrO3 is varied while Order for H Compare expt and where H is varied while 0 00535 0 0107 0 0107 0 0214 and The reaction is The reaction is and are constant and The reaction is order in I are constant order in BrO3 are constant order in H

1 The balanced chemical equation for the formation of nitrogen dioxide is 2 NO g O g 2 NO g In a particular experiment the initial concentration of NO is 0 0152 M After 11 7 min at 25 C the concentration is 0 0131 M What is the rate of the reaction in units of M s over this time interval 8 pts

0 The decomposition of hydrogen peroxide is described by the equation 2H O aq 2H O 1 O 8 The reaction is first order in H O It takes 10 0 hours for the concentration of H O to drop from 0 500 M to 0 250 M How many hours are required for the concentration of H O to drop from 0 400 M to 0 100 M A 38 0 h B 24 0 h C 20 0 h D 12 0 h

Gaseous Radon 222 forms in soil As it rises from the soil it can be trapped in basements below homes This gas an alpha emitter decays into Po 218 once inhaled by people it can cause lung cancer A sample of gas is tested for Rn 222 The 1 2 life of Rn 222 is 3 823 days After 63 days the sample is found to contain 3 50 108 g of Rn 222 How many grams of Rn 222 were initially present g How many grams of Po 218 have been formed

Which of the following substances has a Van t Hoff factor i equals to 13 Sodium chloride Ethanol O Calcium chloride All of the choices

19 Look at the diagram below What is the heat of reaction AH Potential Energy kJ mol 100 90 80 70 60 50 40 30 20 10 20 KJ mol 30 KJ mol 50 KJ mol 80 KJ mol 100 KJ mol Reaction Coordinate

10 points A wooden object from a prehistoric site has a carbon 14 activity of 5 counts per minute cpm compared to 40 cpm for new wood If carbon 14 has a half life of 5730 yr what is the age of the wo For the toolbar press ALT F10 PC or ALT FN F10 Mac BIU S Paragraph V Arial V 10pt 1 T Sa

2 points The attractive forces are weakest in liquids gases solids Previous

Which of the following affects reaction rates Mark all that app solubility O temperature surface area concentration catalyst

Which of the following is the best description of a chemical reaction When two molecules collide with enough force they shatter into O individual atoms Later these atoms join up in new combinations to form new substances When two molecules collide with enough force old chemical bonds are broken and new bonds form resulting in one or more new substances When molecules of a substance move slowly enough they link together to form a crystalline structure When two atoms collide with enough force their nuclei fuse together forming new substances and releasing tremendous amounts of energy

The reaction of 2N O g 4NO g O g is experimentally determined to be first order What experimental data would support this conclusion L Plotting Ln N Os vs time would be linear Doubling the initial concentration of N2O5 would yield a quadrupled initial rate III The half life is independent of the initial concentration Land III Only III Only 1 II and III Only IL

Reaction Rates Test Summative Assessment Please label the energy diagram by dragging the correct option to the correct location Please note that not all options will be used PE ki 100 80 40 20 Progress of the reaction Read ants Reaction Rate

How does decreasing the temperature of the reactants affect the rate of a reaction does not affect reaction rate O not enough information provided to answer O decreases reaction rate O increases reaction rate

Reaction Rates Test Summative Assessment Which of the following methods will usually cause a reaction to speed up O Combining the reactants at a lower temperature Reducing the concentration of reactants O Grinding one of the reactants into a powder Removing the catalyst

Enter your answer in the provided box What would be the 4C activity in a 2700 year old wooden object Assume that the 4C activity of an equal mass of fresh cut wood is 13 7 disintegration per second