1 The bacterium Nitrosomonas sp first converts ammonia NH3 to nitrite NO2 a What is the oxidation number of nitrogen in NH3 b What is the oxidation number of nitrogen in NO2 c Balance the half reaction under basic conditions NH3 NO2 3 3 NH 7OH NO 5H O 6e 2 Find the oxidation numbers for the following a chlorine in Cl O b chromium in Cr O c vanadium in VO and VO d cobalt in Co OH e chromium in Cr OH 1 6 5 5 3 3 3 Identify what is being oxidized what is reduced which is the oxidizing agent and reducing agent Zn s CuSO4 aq ZnSO4 aq Cu s Oxidized Zn 0 2 Reduced Cu 2 0 Oxidizing agent Cu Reducing agent Zn 4 Consider the redox reaction 3Cu 2 2Al 2Al 3 3Cu How many electrons are transferred in the balanced reaction Ans 6 electrons 5 Given the following oxidation reduction reaction 2 aq Cr3 aq VO2 VO2 aq Cr2O7 aq Identify The reagent being oxidized V The reagent being reduced Cr The number of electrons transferred 6 e Balance the equation in acid solution 6 Complete and balance the following redox reaction in acidic solution As s H2AsO4 aq AsH3 aq 7 Consider the voltaic cell with the following components and identify each statement as true or false Ag e Ag 0 80V Zn2 2e Zn 0 76V A T B T C F D T E F 8 Write the following reaction in terms of cell notation 3 Pb aq 2 Al s 3 Pb s 2 Al aq Al s Al aq Pb aq Pb s 9 a What is E cell for the reaction Au s 3 Ca aq 2 Au aq 3 Ca s Ans 4 37V Ecell E cathode E anode 2 87 1 5 b Using the reduction potentials identify which species is the best oxidizing agent and reducing agent Ans Oxidizing agent Au Reducing agent Ca 10 Calculate Eo cell for each of the following balanced redox reactions and determine whether the reaction is spontaneous as written a O2 g 2H2O l 4Ag s 4OH aq 4Ag aq Eo 0 4 V nonspontaneous b Br2 l 2I aq 2Br aq I2 s Eo 0 55 V spontaneous know how to determine anode and cathode with given reduction or oxidation potentials 11 Consider the following reaction Cu s 2Ag aq Cu2 2Ag s If Ag 1 0M and Cu2 0 020M what is the cell potential at 20 C Ag e Ag E 0 80 Cu2 2e Cu E 0 34 12 What is the equilibrium constant K at 298K for an electrochemical cell when E 0 025 V and n 3 13 Calculate G and E Cell for this redox reaction with an equilibrium constant of K 4 6 10 2 at 298K Mn Zn2 Mn2 Zn 14 Given the following reaction 2 Al s 3 Mn2 aq 2 Al3 aq 3 Mn s The standard cell potential E cell is 0 48 V the concentration of Al3 is 1 0 M What is the E value when concentration of Mn2 is 0 05 M Assume T is 298K 15 A galvanic cell consists of a silver electrode in a 1 0 M Ag solution and a magnesium electrode in a 1 0 M Mg2 A schematic of the cell as well as the standard reduction potentials for Ag and Mg2 are given below a What is the overall balanced reaction that occurs in the cell b What is the flow of electrons element to element in the cell c Which half cell is the anode and which is the cathode d What is the standard cell potential for this reaction 16 a F b F c T d F 17 Write a nuclear equation for the indicated decay of each of the following nuclides A 210 Ra undergoes alpha decay B 103 Pd undergoes electron capture C 15 O undergoes positron emission 18 What nuclide undergoes neutron emission to form 87 Br 19 235 U undergoes fission by one neutron to produce 133 Sb 3 neutrons and what other nuclide 20 A radioactive sample contains 1 55g of an isotope with a half life of 3 8 days What mass of the isotope will remain after 5 5 days Assume no excretion of the nuclide from the body 21 Tritium 3H is used in glowing EXIT signs located where there is no electricity for light bulbs If the half life of tritium is 12 26 years and the percentage of the original quantity of the isotope remaining is 35 1 what amount of time in years has passed 22 The half life of 18F is 109 7 minutes Radiolabeled Prozac were administered to a patient for a PET scan at 8 00 A M on Monday Upon further examination at 2 04 P M the same day what level activity percentage would remain compared to its original administration 23 Ga Gallium has Z 31 so Ga 62 has a 31 protons 62 31 31 neutrons n p 1 0 which is low for this b Likely decay decay or electron capture proton neutron mass range proton rich atomic number decreases by 1 Answer a Zn 62 Zinc 62 Z 30 24 Answer c decay or electron capture 25 Answer b decay 26 Sulfur 35 is a radioactive nuclide commonly used in radiolabeling for biological studies The half life of sulfur 35 is 87 0 days What mass of sulfur 35 remains from an initial sample of 200 mg of Na SO after 174 0 days Assume the atomic mass of S is 35 0 27 If 45 0 of a sample of carbon 14 decays in 2 40 hours what is the half life of this isotope in hours
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