Chemical kinetics Questions and Answers

NAI 14 33 8833 1 4 RA 5000 N O vs Time s BOX Time 1 PO MU T 1500 3 000 2 500 2 000 1 500 1 000 0 500 0 000 0 20x30 2500 500 BLOWERD 1000 BACKE 4 80000 EKKINU 1 N O3 vs Time s 10000 1500 Time 1 In N O vs Time s 500 2000 2500 1900 Time 1

Mg Mg HCL FO HO B MgCl H 20140

Potential Energy 400 O A 300 B 200 100 Reactants None of the above Activated complex a Reaction Pathway b Use your knowledge of the collision theory and use the potential energy diagram given to answer questions 1 through 5 Which letter represents the activation energy c Products

The rate of a reaction depends upon O All of the above The temperature of the reaction O The concentration of the reactants O The nature of the reactants

1 First we will build a model for the total amount of drugs in the gut At time t 0 10mg of the drug is present in the gut From the gut it passes slowly into the blood The passage of the drug to the blood has first order kinetics that is every hour 42 of the drug remaining in the gut is passed from the gut into the blood No more pills are taken so no extra drug is added to the gut Let at be the sequence representing the amount of Adderall XR in the patient s gut t hours after the pill was taken Write down a recursion relation for at 2 Find an explicit formula for at 3 Calculate the time at which the amount of drug remaining in the gut drops to 1 of its starting value that is find t for which 0 01g

27 a How many units of hexokinase must be added to 1 ml of reaction volume to use up 95 of 8x10 M glucose in 25 min K 4 7 x 10 M b How long would it take 1 0 unit ml to use up the same amount of glucose

23 Vax at 21 and 37 C was 140 nmoles X literx min and 400 nmoles x liter x min respectively Calculate a the activation energy and b the Quo value between 25 and 35 C

The half lives of different radioisotopes are given in the table Half life min Radioisotope argon 44 lead 196 potassium 44 indium 117 12 37 22 43 How long would it take in minutes for the amount of argon 44 to decrease from 92 0 mg to 11

catalyst transition state collision theory rate activation energy inhibitor 1 synonym for activated complex 2 speed of a change that occurs over time 3 substance that slows down a reaction 4 Particles can react to form products when they collide provided they have enough kinetic energy 5 substance that increases the rate of a reaction without being used up 6 minimum energy particles must have in order to react

An energy diagram for a reaction both with and without an enzyme is given below Used Released Energy A B Without enzyme With enzyme Time AB

4 Write a complete balanced chemical equation for the reaction between sodium sulfide and chromium III chloride be sure to include the states of matter Na S aq CrC1 aq a Identify the precipitate formed during this reaction by giving the chemical formula and chemical name for this substance b Show by calculation which reactant is the limiting reactant when 91 3 g of sodium sulfide are allowed to react with 139 g of chromium III chloride Na S c Calculate the theoretical mass of the precipitate formed during this reaction 78 1 g d Calculate the percent yield for the reaction given that 62 8 g of the precipitate are recovered from the reaction 80 4 e Calculate the mass of excess reactant remaining from this reaction 16 g

For the following reaction 68 1 grams of potassium hydroxide are allowed to react with 37 7 grams of phosphoric acid potassium hydroxide aq phosphoric acid aq potassium phosphate aq water 1 What is the maximum amount of potassium phosphate that can be formed What is the FORMULA for the limiting reagent What amount of the excess reagent remains after the reaction is complete grams grams

In solution chlorine dioxide CIO2 aq and hydroxide ions OH aq react to form chlorate ions CIO3 aq chlorite ions ClO aq and water The balanced chemical equation for this reaction is 2 CIO2 aq 2 OH aq CIO3 aq CIO aq H O 1 The reaction is found to be second order with respect to chlorine dioxide and first order with respect to hydroxide ions a Write a rate equation for the reaction Place your answer in blank 1 b What is the overall order of the reaction Place your answer in blank 2 c How would doubling the concentration of chlorine dioxide affect the reaction rate Place your answer in blank 3 d How would doubling the concentration of hydroxide ions affect the reaction rate

In the following reaction what is the rate equation in terms of molecules that can easily be measured C4H8O2 CH 0 C4H7O O v k C4H80 CH30 Ov k C4H70 V Ov k2 C4H60 HOT Ov keff O C4H8O CH3CH H ve k2 C4H702 1 C4H60 HO k K 1 k C4H7O2 CH3OH C4H6O HO fast slow

C3H8 5023 CO2 4H O which of the following is a valid expression for the reaction rate A A C3H8 At B 5 A 0 At C A 0 5 At D 4 A H O At E 3 A CO At The data in the table below were obtained for the reaction involving reactants A and B Experiment Number A B Initial Rate M s 1 2 3 0 100 20 0 200 20 0 200 40 0 020 0 040 0 320 The concentrations of A and B in the table are given in the usual molar units M Based on these data what is the appropriate rate law for the reaction

Balance the following half reaction in acidic solution and then classify as oxidation or reduction 8 pts Cr aq Cr O aq

Referring to the following table for hypothetical reactions identify the strongest oxidizing agent A A aq A A aq B C aq C D4 aq D B2 aq Reduction Half Reaction A aq e A s B2 aq 2e B s C3 aq e C2 aq D4 aq 4e D s E V 1 33 0 87 1 82 1 59 E none of the above they are all reducing agents

Use this diagram below to answer Questions 2 through 4 2001 160 PE KJ 120 80 40 155 kJ 40 kJ 172 kJ 112 kJ 102 kJ

For an instantaneous rate of change geometry can be used to approximate the value The symbol an instantaneous change in a value 1 What is true about the reactant concentration over time 0 20 0 15 mol 0 05 A Reactant At 3 Circle the time at which the magnitude of the instantaneous rate of change is the lowest i e during which time is the tangential slope least negative This is the time when the reactant is changing least over time 0 00 constant Concentration of reactant vs time Rate Slope 1 06x10 2 M sec d Reactant dt 10 Time sec 15 is needed but algebra is used to denote 20

Reaction Rates Reaction rates are measured in units of rate 1 Determine the average rate of product formation between 50 and 150 seconds 2 Is the tangential slope positive or negative for Product Reactant at a single time is the The The slope over a range of time is the Connection to Mathematics Physics Concentration mol L Slope is the rate of change The symbol 0 10 0 08 0 06 0 04 0 02 0 00 which is to 50 rate 100 Time s rate delta means for a range average rate of change product reactant SE PRE Example A car decreases speed from 35 m s to 15 m s over a period of 5 seconds What is the car s acceleration average rate of change for velocity Example The concentration of CHF product increases from 0 20 mol L to 0 80 mol L tion time Petermine the average reaction rate for this time

Potential energy kJ ollowing information PE of Q R 150 kJ PE of S T 250 kJ PE of the activated complex 375 kJ 400 350 300 250 200 150 100 50 0 Reaction coordinate a Is the forward reaction endothermic or exothermic Calculate the value of AH for this reaction

Hydrogen peroxide decomposes spontaneously to yield water and oxygen gas according to the reaction equation 2 H O aq 2H O l O g The activation energy for this reaction is 75 kJ mol In the presence of a metal catalyst the activation energy is lowered to 49 kJ mol At what temperature would the non catalyzed reaction need to be run to have a rate equal to that of the metal catalyzed reaction at 25 C

For the multi step reaction A B C D the rate limiting step is unimolecular with A as the sole reactant If A and B are both 0 165 M then the rate of reaction is 0 0090 M s What is the rate of the reaction if A is doubled rate Starting with the original concentrations what is the rate of the reaction if B is halved rate Starting with the original concentrations what is the rate of the reaction if A and B are both increased by a factor rate

The rate constant for this second-order reaction is 0.820 M-¹. s-¹ at 300 °C. A --> products How long, in seconds, would it take for the concentration of A to decrease from 0.950 M to 0.220 M?

A certain reaction has an activation energy of 35.30 kJ/mol. At what Kelvin temperature will the reaction proceed 3.00 times faster than it did at 343 K?

The rate constant for this zero-order reaction is 0.0400 M s¹ at 300 °C. A --> products How long (in seconds) would it take for the concentration of A to decrease from 0.890 M to 0.220 M?

After 44.0 min, 41.0% of a compound has decomposed. What is the half-life of this reaction assuming first-order kinetics?

Describe and explain the possible effect on your results (yield and purity) of the following experimental errors or variations: a. The reaction flask you used for the preparation of m-toluoyl chloride was wet b. Instead of 3.0 M NaOH, you used the same amount of 1.0 M NaOH for the reaction step c. You didn't stir the reaction mixture during the reaction of diethylamine with acid chloride

The Lewis structure for carbon monoxide is:C=O:This structures shows A) 4 lone pairs and 1 bonding pair. B) 4 lone pairs and 3 bonding pairs. C) 2 lone pairs and 3 bonding pairs. D) 2 lone pairs and 1 bonding pair. E) none of the above

The activation energy for a particular reaction is 102 kJ/mol. If the rate constant is 1.35 x 10s¹ at 308 K, what is the rate constant at 273 K?

For the decomposition of nitrous oxide at 565 °C 2 N₂0 2 N₂ + 0₂ the average rate of disappearance of N₂O over the time period from t = 0 s to t= 522 s is found to be 1.54x10-³ M s¹_ The average rate of formation of O₂ over the same time period is Ms-1.

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.

Dichlorodifluoromethane (CF₂Cl2) is a CFC (chlorofluorocarbon) molecule that used tobe used as a refrigerant, though people discovered that CFCs harm Earth's ozone (O3)layer, which protects us from the sun's harmful UV rays. Another type of harmful CFC is CHF₂CI, called chlorodifluoromethane. The boiling point of CHF₂Cl is about -41°C, and the boiling point of CF2Cl2 is -30°C. CHF₂CI has a [Select] boiling point than CF₂Cl₂ CHF₂CI has a [Select] vapor pressure than CF₂Cl₂ thus, we can conclude that CHF₂Cl has [Select] IMF than CF₂Cl2

Two volatile substances, A and B are dissolved in one another and the resulting solution has a vapor pressure of 137 torr. If the mole fraction of B is 0.230 and the vapor pressure of pure B is 162 torr, what is the vapor pressure of pure A in torr?

The rate at which a certain drug is eliminated by the body follows first-order kinetics, with a half life of 85 minutes. Suppose in a particular patient the concentration of this drug in the bloodstream immediately after injection is 0.60 ug/mL. What will the concentration be 425 minutes later? Round your answer to 2 significant digits.

NaHCO3(s)+HC2H3O2(aq) → NaC2H3O2(aq) +H2O(l) +CO2(g) A student designs an experiment to study the reaction between NaHCO, and HC₂H₂O₂. The reaction is represented by the equation above. The student places 1.26 g of NaHCO, in a flask and adds 60.0 mL of 0.875 M HC,H,O,. The student observes the formation of bubbles and that the flask gets cooler as the reaction proceeds. a. Identify the reaction represented above as an acid-base reaction, precipitation reaction, or redox reaction. Justify your answer. b. Based on the information above, identify the limiting reactant. Justify your answer with calculations.

Chymotrypsin is a protease that hydrolyzes proteins. It is active in the small intestine at an optimum pH of 8.0. How is the rate of a chymotrypsin-catalyzed reaction affected by using more enzyme in the reaction mixture? The rate would increase. The rate would first increase and then it would decrease. The rate would be unchanged. The rate would decrease. I DON'T KNOW YET

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 3.50×10-8 g of Rn-222. How many grams of Rn-222 were initially present? _________g How many grams of Po-218 have been formed? _________g

Two different reactions begin with equal concentrations of their respective reactants, A and C. Both reactions proceed, but reaction 1 has a faster initial rate than reaction 2. Both reactions are allowed to react for an extended period of time. Reaction 1: A⇒ B faster initial rate Reaction 2: C ⇒ D slower initial rate Identify the conclusion that cannot be made based on the information given. Reaction 2 has a smaller concentration of products at equilibrium. Reaction 1 and reaction 2 can both reach equilibrium. The concentrations of C and D do not change at equilibrium. Reaction 1 reaches equilibrium more quickly than reaction 2.

Thorium, a rare element in the earth's crust, has over seven radioactive isotopes. Of of these 22790Th has a half-life of 18.68 days. Calculate the decay constant. _____d-¹ What percent of Th-227 will be left after 28 days? _____% When 15.5 % is left, how much time has passed? _____days

A physical quantity X depends on two physical quantities A and B according to the relation X = eAB. Find maximum percentage error in X, if A = (10 + 0.001) and 8= (20 ± 0.002). Answer:

Using the reaction and data in the table below answer the following series of questions. i i. 2 NO (g) + O₂ (g) Reaction 1 2 3 first ✓ [Select] zeroth second 02 NO conc. conc. third 2 NO₂ (g) 0.250 0.200 M M *conc = concentration Initial Rate (M/s) 0.500 0.200 2.2 x M M 10-4 5.6 x 10-5 0.250 0.400 1.1 x M M 10-4 er er

A solution was prepared with 0.216 mol of pyridinium fluoride (C,H, NHF) and enough water to make a 1.00 L. Pyridine ( C₂H₂N) has a K₁ = 1.70 x 10-⁹ and HF has a K₂ = 6.30 × 10-4. Calculate the pH of the solution.

A saturated solution of copper(1) cyanide, CuCN, has [Cu+] = 1.9x10-10 M and [CN] = 1.9x10-10 M. ▼ Part A What is the value of Ksp for CuCN? Express your answer using two significant figures.

Which of the following diagrams correctly represents an endothermic reaction? (The "ve" is a shorthand to show you the sign of the enthalpy change). a. b. C. d. Reactants Enthalpy All-ve 17 Products Enthalpy Reactants Eathalpy All ove Products Enthalpy AH-ve LF Reactints Reactants Products Products all ove

Identify how each of the following changes would affect the rate of the following reaction: Drag the appropriate items to their respective bins. Add some NO(g). 2NO(g) + 2H₂(g) →N2(g) + 2H₂O(g) Lower the temperature. Add a catalyst. Remove some H₂(g).

13. Calculate the enthalpy change, in kJ/mol for the reaction. H₂(g) + 1/2O₂(g) → H₂O(g) Data of bond energy: H-H= +436 kJ/mol O=O= +498 kJ/mol H-O= +464 kJ/mol a. -243 kJ/mol b. -6 kJ/mol c. +6 kJ/mol d. +221 kJ/mol

A sample of 0.6760 g of an unknown compound containing barium ions (Ba²+) is dissolved in water and treated with excess sodium sulfate. After the reaction goes to completion, 0.4105 g of a solid residue are obtained. Based on data given determine the percent by mass of Ba in the original unknown compound. (Enter your answer in the space provided below and submit all supporting work in order to receive full credit) % Ba in sample:

If 2.25 moles of H₂ and 1.55 moles of O₂ react how many moles of H₂O can be produced in the reaction below? 2 H₂(g) + O₂(g) → 2 H₂O(g)

Imagine two samples of acetic acid (CH₂COOH) in water, both with the same molar concentration. One sample has a temperature of 273 K and one sample has a temperature of 27°C. Which sample's molecules have a higher internal energy? Is this greater internal energy due to greater potential or kinetic energy of the molecules? Explain.