Chemical kinetics Questions and Answers

6 Show that the half life of a first order reaction is independent of starting concentration Describe a real world case where this might be relevant

Reaction Order Determine the reaction order for the graphs in the image below B A slope k A Time In A slope k Time 1 A C slope k Time Match the graph to the the reaction order Graph B Graph C Graph A Second order Cannot be determin this graph Zeroth order Half order First order 111

8 Cl 8 xperiment COCI 8 CO M 0 12 0 24 0 12 CI M 0 20 0 20 0 40 Initial Rate M s 0 121 0 241 0 483 14 Hat is the reaction order exponent for CO Type a whole number Type your answer 3 points What is the reaction order exponent for Cl Type a whole number Type your answer 15 3 points What is the rate constant without units Type a whole number Do not include units Type your answer 16 2 points What is the correct unit for the rate constant M 15 1 M S 1 M 5 1

wing data CO g Cl g COC12 8 Experiment CO M 0 12 0 24 0 12 Cl M 0 20 0 20 0 40 Initial Rate M s 0 121 0 241 0 483 14 Type a whole number Type your answer 3 points What is the reaction order exponent for Cl Type a whole number

For a chemical reaction the rate constant at 37 0 C is 0 003800 s 1 while the rate constant at 60 0 C is 0 012454 s1 Calculate the activation energy in kJ m Do not report units in your answer Report your answer with 2 places past the decimal point

3 points The reaction A B is first order with a half life of 0 910 seconds What is the rate constant of this reaction in s Do not report units in your answer Report your answer with 3 places past the decimal point Type your answer

An energy diagram can be used to summarize several concepts about chemical reactions Consider the reaction 2A 25 kcal mol 2B C and its energy diagram 60 50 40 kcal mol 30 20 This is an 10 o course of rx D The potential energy of the reactants is The potential energy of the products is The change in potential energy AE is reaction since energy must be added to create product ndothermic Gunthermic D 15 kcal mol E 40 kcal mol F 25 kcal mol

million years to over 4 5 billion years with precision in the 0 1 1 range The U Pb dating method relies on two separate decay chains one of which is the actinium series from 235U to 207Pb with a half life of 704 million years V 2nd attempt See Periodic Table See Hint Geologists unearth a sample of zircon that appears to be a closed system They find 0 730 grams of 207 Pb for 1 000 grams of 235 U present Approximately how old is the sample

5 One of the byproducts of the production of nuclear grade materials during the cold war was tritium H which is a radioactive isotope of hydrogen with half life of 12 32 years It is estimated that the Hanford Nuclear Reservation produced 10 6 kg of tritium in 1969 What mass of tritium remains today

3 1 point If a 30g sample of a radioactive isotope has undergone two 2 half lives what mass of the radioactive sample will still remain Type in the exact answer with NO units

The rate of a chemical reaction always remains the same from start to finish True False

O c O d e Al O3 HC AlCl3 H O HCI H O Al O3 HCI AICI3 H O 1 HC The value of Kc for the following reaction is 0 73 SO2 g NO g SO3 g NO g The value of Ke at the same temperature for the reaction below is 3SO2 g 3NO2 g 3SO3 g 3NO g Time le In the coal gasification process carbon monoxide is converted to carbon dioxide via the following rea

O e 4 The first order reaction A B is initiated with A o 2 708 M It takes 58 8 seconds for the reaction to proceed until A 0 607 M Based on this information what is the half life for this reaction Please report your answer to 3 significant figures S The mechanism for formation of the product X is

O c X O d B O e D For the reaction 3A 2B a plot of 1 A vs time is linear with a slope of 0 416 M s This reaction is initiatec with A o 2 193 M and B 0 000 M What is the concentration of B after 47 7 seconds Please report your answer to 3 decimal places M

The rate of a certain reaction is given by the following rate law rate k N 0 Use this information to answer the questions below What is the reaction order in N What is the reaction order in 03 What is overall reaction order At a certain concentration of N and O3 the initial rate of reaction is 30 0 M s What would the initial rate of the reaction be if the concentration of N were halved Be sure your answer has the correct number of significant digits The rate of the reaction is measured to be 0 880 M s when N 0 70 M and 03 0 80 M Calculate the value of the rate constant Be sure your answer has the correct number of significant digits 0 M 2 5 S x10 X

A chemistry graduate student is studying the rate of this reaction CICH CH CI g CH CHCI g HC1 g 1 He fills a reaction vessel with CICH CH Cl and measures its concentration as the reaction proceeds time milliseconds 0 10 20 30 CICH CH CI 40 0 0700M 0 0252M 0 0154M 0 0111 M 0 00865 M Use this data to answer the following questions Write the rate law for this reaction Calculate the value of the rate constant k Round your answer to 2 significant digits Also be sure your answer has the correct unit symbol rate 0 D D X 5 C

O e M s The data in the table below were obtained for the reaction A B P Expt 1 2 3 A M Select one O a 0 O b 1 O c 2 O d 3 O e 4 0 361 0 722 0 361 B M 0 244 0 244 0 488 The order of the reaction in A is Initial Rate M s 0 0232 0 0464 0 0928

Dinitrogen tetraoxide partially decomposes according to the following equilibrium N O4 g 2NO2 g An empty 1 00 L vessel is charged with 0 104 mol of N O4 g At equilibrium 0 0912 mol of N2O4 g remains Kc for this reaction is Record your answer to 3 significant figures

25 Ozone O3 can oxidize HSO3 aq as represented by the equation below HSO3 aq O3 aq HSO4 aq O g A solution is prepared in which the initial concentration of HSO3 aq 6 4 x 10 M is much larger than that of O3 aq 1 0 x 105 M The concentration is monitored as the reaction proceeds and the data are plotted in the graph below 0 1 0 x 10 5 8 0 x 10 6 6 0 x 10 6 4 0 x 10 6 2 0 x 10 6 0 0 0 01 0 02 0 03 0 04 0 05 0 06 0 07 0 08 0 09 0 10 Time s The data are consistent with the following rate law rate k 03 a Based on the graph above determine the half life of the reaction b Determine the value of the rate constant k for the rate law Include units in your answer c Considering the relative concentrations of the reactants briefly explain why the data in the graph are also consistent with the following rate law rate k 03 HSO3 d Briefly describe an experiment that could provide evidence to support the rate law given in part c

Which best describes the activation energy on the graph below Potential Energy T 2 Reaction Progress 3 OA The difference between the x axis and 2 OB The vertical difference between 1 and 2 C The vertical difference between 1 and 3 OD The vertical difference between 2 and 3

2C1O2 aq 2OH aq CIO3 aq CIO2 aq H O l Expt 1 2 in the table below were obtained for the reaction 3 CIO M OH M Select one a 0 b 1 c 2 d 3 e 4 0 060 0 020 0 020 0 030 0 030 0 090 What is the overall order of the reaction Initial Rate M s 0 0248 0 00276 0 00828

A worker in a laboratory wingly became exposed to as imple or emitter t1 2 8 07 days The mistake was realized 28 days after the accidental exposure at which time the activity of the sample was 25 6 x 105 Ci g The safety officer needed to know how active the sample was at the time of the exposure Part 1 Your answer is correct Choose the equations needed to calculate the activity In A A kt k t1 2 ln2 k In2 t1 2 In A A kt eTextbook and Media Hint Attempts 1 of 15 used

If we begin with 3 00 mg of iodine 131 t1 2 8 07 hr how much remains after four half life periods pada mg

4 5 Which of the following correctly pairs a phase of matter with its description A Solid Particles have no motion B Liquid Particles expand to fill any container in which they are placed C Gas Particles have higher amounts of energy than when in the liquid phase D Liquid Particles are more strongly attached to one another than when in the solid phase The diagram below represents a phase change for some copper atoms Which of the following phase changes are the copper atoms undergoing A gas to liquid B liquid to gas C solid to liquid D liquid to solid 6 When a sample of a gas is cooled it condenses into a liquid In which of the following ways do the molecules of the original gas sample compare with the molecules of the liquid a ruler A The molecules are larger as a gas than they are as a liquid B The molecules weigh less as a gas than they do as a liquid C The molecules move faster as a gas than they do as a liquid D The molecules are closer together as a gas than they are as a liquid The addition of 500 J of energy to a block of iron causes a rise in the average kinetic energy of the atoms in the block Which of the following instruments can best be used to observe this change a balance a thermometer a graduated cylinder

The reaction A B 2 C has the rate law rate K A B By what factor does the rate of reaction increase when A remains constant but B is doubled

4 For the reaction A 2B The reaction is 2nd order in A and 1st order in B C D a Write the rate expression for the reaction b If the concentration of A is doubled what will happen to the rate c If the concentration of B is doubled what will happen to the rate

3 The reaction 2NO g 2H g Was studied at 904 C and the data in the table were collected a Write the general rate equation for this reaction b Solve for the exponents c Solve for the rate constant d What is the initial rate when NO 0 350 M and H 0 205 M NO H Experiment 1 2 3 4 N g 2H O g 0 420 0 210 0 210 0 105 mar 0 122 0 122 0 244 0 488 Initial Rate M s 0 136 0 0339 0 0678 0 0339

Question 3 4 ptsx 5 In the hypothetic reaction 2A s 3B aq C g 2D g energy If the experiment decided that the reaction is second order to B and first order to C how would the reaction rate equation be expressed Sketch the reaction process vs potential energy and mark the reactants products and ii iii iv activation energy on the graph If the concentration of B is increased how the reaction rate will be affected Explain your answer If the system temperature is increased how the reaction rate will be affected Explain your answer vi If a catalyst is added to the reaction system how the reaction will be affected Explain your answer

Use the information to answer the following question Several groups of Chemistry students are tasked with producing aluminum chloride using solid aluminum as a reactant The teacher provides the students with two forms of aluminum powder and solid chunks Which type of aluminum should the students plan to use in order to increase the reaction rate Solid chunks because the greater surface area will allow more collisions between reactants to occur Powder because the lower surface area will allow more collisions between reactants to occur Solid chunks because the lower surface area will allow more collisions between reactants to occur Powder because the greater surface area will allow more collisions between reactants to occur

11 2 points The enthalpy is defined as the system s internal energy True False

13 A student analyzed a first order reaction and obtained the graph at the right but forgot to label the axes What should the labels be for the X and Y coordinates respectively a time In A b time A c temperature A d temperature In A e time 1 A 14 For the gaseous reaction 2A B the results of a plot of In A versus time is in the figure What conclusion regarding the reaction order may be made a the reaction is not first order b the reaction is first order In A c the reaction is not second order time d the reaction is second order c the reaction is third order

Learning Goal To learn how to use the Nernst equation The standard reduction potentials listed in any reference table are only valid at the common reference temperature of 25 C and standard conditions of 1 M for solutions and 1 atm for gases To calculate the cell potential at nonstandard conditions one uses the Nernst equation 2 303 RT nF E E log10 Q where E is the potential in volts E is the standard potential at 25 C in volts R 8 314 J K mol is the gas constant T is the temperature in kelvins n is the number of moles of electrons transferred F 96 500 C mol e is the Faraday constant and is the reaction quotient At the common reference temperture of 298 K substituting each constant into the equation the result is E E 0 0592 Vlog10 n at 55 C where Fe2 2 90 M and Mg2 0 310 M Part A What is the value for the reaction quotient Q for the cell Express your answer numerically View Available Hint s Q Submit Part B VAE What is the value for the temperature T in kelvins Express your answer to three significant figures and include the appropriate units View Available Hint s

In a study of the decomposition of hydrogen iodide on a gold surface at 150 C HI g 2 H g 1 9 the following data were obtained HI M seconds 0 261 0 0 131 518 6 55x10 2 780 3 28x10 2 910 Hint It is not necessary to graph these data 1 The observed half life for this reaction when the starting concentration is 0 261 M is starting concentration is 0 131 M is 2 The average rate of disappearance of HI from t 0 s to t 518 s is Based on these data the rate constant for this 3 The average rate of disappearance of HI from t 518 s to t 780 s is a order reaction is Ms Ms s and when the

hank 1 24 x 10 1 49 x 103 10 12 14 16 In k vs 1 T 000050001 00015 0 002 0 0075 0 003 y 12391x 31 321 1 T K 0 0075 16 004 Using the graph and linear function given determine the Activation Energy Ea in J mol

2 Give the theoretical rate equation for the forward direction when all are gases except for water AND PH3 4 PH3 liq 2 H 90 2 P 05 8 H O liq 25 kj The rate requires the collision interactions of O molecules This is also reflected as the exponents in the rate equation ratef k 1 0 N 1 PH3 H and

1 Give the theoretical rate equation for the forward direction when all are gases except for water 4 PH3 2 H 90 2 P 05 8 H O liq 25 kJ The rate requires the collision interactions of O molecules This is also reflected as the exponents in the rate equation rate k 140 1 PH3 19 H and

particular reaction is proposed to be second order in A What plot would support this conclusion A a linear plot of A vs time B a linear plot of In A vs time C a linear plot of A vs time D a linear plot of 1 A vs time

A certain reaction has an activation energy of 57 85 kJ mol At what Kelvin temperature will the reaction proceed 4 00 times faster than it did at 365 K T

2NO g O g 2NO g She collects the following data Trial 1 2 3 on Initial Concentration of NO M 0 0250 0 0500 0 0250 Initial Concentration of O M 0 0253 0 0253 0 0506 What is the rate equation for this reaction Instantaneous Reaction Rate M s 0 0281 0 112 0 0562

nder certain conditions the rate of this reaction is zero order in ammonia with a rate constant of 0 0031 M s 2 NH3 g N g 3H g Suppose a 3 0 L flask is charged under these conditions with 150 mmol of ammonia How much is left 4 0 s later You may assume no other reacti mportant Be sure your answer has a unit symbol if necessary and round it to the correct number of significant digits

USING THE SAME DATA AS BEFORE A chemistry student reacted magnesium metal Mg and acetic acid in varying concentrations and temperatures The following data shows their results Starting Temperature of Acid Time for Mg to React min Trial 1 2 3 4 Amount of Mg g B 5 grams 5 grams 5 grams 5 grams Concentration of Acid 111 Very Low Low Medium I T T High 24 C 24 C 24 C 24 C 5 min The student repeats the experiment reacting 5g of Mg with HIGH concentration of acid Instead of changing the concentration like the previous question suggest another change that would make the reaction happen faster than in Trial 4 Use molecular collisions to explain why your suggested change would work I L min 3 min 2 min

The first step in the production of nitric acid is the combustion of ammonia 4NH3 g 50 g 4NO g 6H O g If the rate of the ammonia being consumed is 3 20 x 10 2 M what would the rate of for NO g show answer as a decimal

b The half life for the beta decay of potassium 40 is 1 3 109 years What is the rate constant for this decay

b Iodine 131 which is used to treat thyroid cancer has a half life of 8 04 days How much time is required for 76 of the isotope to decay Show your work 6 days 3 days 17 days 41 days 52 days a b c d e

For the following diagram select all statements that are true PE kJ 100 80 60 40 20 A B C D Progress of the reaction The reaction is endothermic The activation energy of the reaction is 100kJ The energy of the reactants is 40kJ The energy change of the reaction is 20kJ

004 part 1 of 4 10 0 points Consider the energy diagram Energy kJ 45 0 0 45 Forward Reverse Find A Eforward Answer in units of kJ mol 005 part 2 of 4 10 0 points Find AEreverse Answer in units of kJ mol 006 part 3 of 4 10 0 points Find E Find Ea Answer in units of kJ mol 007 part 4 of 4 10 0 points

The reaction equation is Fe O3 s 2 Al s 2 Fe s Al2O3 s For this reaction AH 851 5 kJ and AS 38 58 J K Which of the following statements is true about the process Enthalpy favours the reactants and entropy favours the products Both driving forces favour the products Enthalpy favours the products and entropy favours the reactants Both driving forces favour the reactants

2 What is the molarity of a solution containing 2 65 moles in 2 00 L

24 This is a potential energy diagram B C Reaction Progress What can be concluded from the potential energy diagram A The reaction produced a covalent compound The reaction produced an ionic compound The reaction was exothermic The reaction was endothermic D O A OD O C Potential Energy Diagram B Energy X ELEASEL

PE KJ 400 200 100 Created by E Lee for Virtual Virginia 2021 497 kJ 175 kJ Reaction Progress The reaction coordinate diagram above has an activated complex AC with a potential energy PE of 705 kJ Imagine that a catalyst is added bringing the AC PE down to 577 kJ What will be the new activation energy in kJ