Chemical kinetics Questions and Answers

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

Select the gas that would have the highest average molecular speed Assume all are at the same temperature O Nitrogen dioxide O Dinitrogen monoxide O Argon O Neon

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 2NO2 17 0 takes place at a certain temperature the rate of reaction of dinitrogen pentoxide is proportional to its concentration as follows d 05 0 0007 05 dt a Find an expression for the concentration N 05 after t seconds if the initial concentration is C 0 0007t Ce B Ce 0 0007t b How many seconds will the reaction take to reduce the concentration of N O5 to 90 of its original value Round your answer to one decimal pla 3289 4 XS

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