Very easy chemistry 2 quiz, chemistry homework help

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Name _________________________________ I.D. Number _______________________ Unit 4 Evaluation Evaluation 04 Chemistry 2 (SCIH 032 062) This evaluation will cover the lessons in this unit. It is open book, meaning you can use your textbook, syllabus, and other course materials. You will need to understand, analyze, and apply the information you have learned in order to answer the questions correctly. To submit the evaluation, follow the directions provided. Matching Match each of the following terms to its correct definition. a. oxidation number b. half-reaction c. oxidizing agent d. reducing agent _____ 1. substance that accepts electrons _____ 2. substance that donates electrons _____ 3. integer related to the number of electrons under an atom's control _____ 4. reaction showing either the reduction or the oxidation reaction a. choose coefficients to make the change in oxidation number equal to 0 b. add the balanced half-reactions to show an overall equation c. assign oxidation numbers to all the atoms d. write the equation showing ions separately _____ 5. the first step in balancing a redox reaction by the oxidation-number-change method Unit 4 Evaluation 143 SCIH 032 _____ 6. the next-to-the-last step in balancing a redox reaction by the oxidation-number-change method _____ 7. the first step in balancing a redox reaction by the half-reaction method _____ 8. the next-to-the-last step in balancing a redox reaction by the half-reaction method Multiple-Choice Select the response that best completes the statement or answers the question. _____ 9. What particles are transferred in an oxidation-reduction reaction? a. b. c. d. _____ 10. What change occurs during oxidation? a. b. c. d. _____ 11. protons ions electrons atoms gain of hydrogen loss of oxygen gain of electrons loss of electrons Which element is reduced in the following reaction? 2PbSO4 + 2H2O  Pb + PbO2 + 2H2SO4 a. b. c. d. lead sulfur hydrogen oxygen _____ 12. The equation Cu  Cu+2 + 2 e- represents a reaction that can be classified as _________. a. b. c. d. _____ 13. redox hydrolysis reduction oxidation What is the reducing agent in the following reaction? 2Na + S  Na2S a. b. c. d. Unit 4 Evaluation Na S Na2S Na+ 144 SCIH 032 _____ 14. What process occurs during the corrosion of iron? a. b. c. d. _____ 15. The oxidation number of magnesium in magnesium chloride is _________. a. b. c. d. _____ 16. –1 0 +1 +2 What is the oxidation number for each atom in NH4Cl? a. b. c. d. _____ 17. Iron is oxidized. Iron is reduced. Iron (III) is oxidized. Iron (III) is reduced. N = +3, H = –4, Cl = +1 N = –3, H = +1, Cl = –1 N = +3, H = +1, Cl = –1 N = –3, H = –1, Cl = +1 In the following unbalanced reaction, which atom is reduced? 2H2O + Cl2 + SO2  2HCl + H2SO4 a. b. c. d. _____ 18. hydrogen oxygen chlorine sulfur Which element increases its oxidation number in the following reaction? 3KOH + H3PO4  K3PO4 + 3H2O a. b. c. d. oxygen potassium phosphorus no changes in oxidation number _____ 19. Which of the following chemical equations represents a redox reaction? a. b. c. d. 2Na + 2H2O  2NaOH + H2 HCl + KOH  KCl + H2O AgNO3(aq) + NaCl(aq)  NaNO3(aq) + AgCl(s) + H2O(l) Fe3+ + 3NO3– + 3Na+ + 3OH–  Fe(OH)3 + 3Na+ + 3NO3– _____ 20. Which of the following types of reactions is always a redox reaction? a. b. c. d. Unit 4 Evaluation acid-base double-replacement combustion neutralization 145 SCIH 032 _____ 21. What is the coefficient for H+ when this half-reaction is balanced? H+ + MnO4-  MnO2 + H2O a. b. c. d. 1 2 3 4 _____ 22. What is the reduction half-reaction for the following unbalanced redox equation? Fe2O3 + CO  Fe + CO2 a. b. c. d. Fe2O3  Fe Fe  Fe2O3 CO  CO2 Fe2O3  CO2 _____ 23. What is the key factor in defining a reaction as an oxidation-reduction reaction? a. b. c. d. transfer of electrons between atoms oxygen as one of the reactants making and breaking ionic bonds precipitation of solid from the reaction solution _____ 24. The half-reaction method is particularly useful for balancing which type of equation? a. b. c. d. dissociation acid-base redox combustion _____ 25. What is a balanced equation for the redox reaction represented by the two halfreactions below? Br2 + 2e-  2BrNa  Na+ + ea. b. c. d. Unit 4 Evaluation Na + Br + e  Na + 2Br Na + Br  Na + 2Br 2Na + Br2  2Na+ + 2BrNa + Br + 2e  Na + 2Br + e 146 SCIH 032 Matching Match each of the following terms to its correct definition. a. anode b. battery c. fuel cell d. half-cell e. cathode _____ 26. the electrode at which oxidation occurs _____ 27. one part of a voltaic cell in which either oxidation or reduction occurs _____ 28. the electrode at which reduction occurs _____ 29. a group of cells that are connected together _____ 30. a voltaic cell in which a fuel substance undergoes oxidation and from which electrical energy is obtained continuously a. electrode b. electrolysis c. salt bridge d. voltaic cell e. dry cell _____ 31. a tube containing a conducting solution _____ 32. a conductor in a circuit that carries electrons to or from a substance other than a metal _____ 33. an electrochemical cell that is used to convert chemical energy to electrical energy _____ 34. a voltaic cell in which the electrolyte is a paste _____ 35. a process in which electrical energy is used to bring about a chemical change Unit 4 Evaluation 147 SCIH 032 Multiple-Choice Select the response that best completes the statement or answers the question. _____ 36. Which of the following metals will be oxidized by calcium ions? a. b. c. d. potassium zinc iron lead _____ 37. Which of these ions is most easily reduced? a. b. c. d. Cu Zn Ni Ca _____ 38. How can a redox reaction be used as a source of electrical energy? a. b. c. d. Two half-reactions must be physically separated. One half-reaction must involve two metals. Two half-reactions must involve more than one electron. One half-reaction must use a metal wire electrode. _____ 39. How is the standard reduction potential of a half-cell determined? a. b. c. d. by direct measurement of the potential with a voltmeter by measuring the voltage of a cell with a standard hydrogen electrode by measuring the voltage of a cell with a standard mercury electrode by connecting two of the half-cells in opposite directions and measuring the voltage _____ 40. At which electrode does oxidation occur in a voltaic cell? a. b. c. d. the half-cell with the greater tendency to acquire electrons the half-cell with the greater tendency to lose electrons the half-cell with the greater value of reduction potential the half-cell with the greater value of standard cell potential _____ 41. The half reaction at a barium electrode is: Ba2+ + 2e-  Ba For a cell using a barium electrode and a hydrogen electrode, E° = +2.90 V. What is the standard reduction potential of the barium electrode? a. b. c. d. Unit 4 Evaluation -2.90 V -1.45 V 1.45 V 2.90 V 148 SCIH 032 _____ 42. In a dry cell, the electrolyte is a _________. a. b. c. d. solid paste liquid gas _____ 43. A cell is built using two electrodes: What reaction occurs at the cathode? Al3+ + 3e Al Cu2+ a. b. c. d. + 2e  Cu E° = -1.66V E° = +0.34V Cu  Cu2+ + 2eCu2+ + 2e-  Cu Al3+ + 3e- Al Al  Al3+ + 3e- _____ 44. How is a lead storage battery recharged? a. b. c. d. A direct current is applied to it. A magnet is held close to it. Alternating current is forced through it. The pressure on it is increased. _____ 45. When a lead storage battery discharges, the concentration of _________. a. b. c. d. sulfuric acid increases sulfuric acid decreases lead sulfate in the battery decreases lead sulfate in the battery remains constant _____ 46. In electroplating, the object to be electroplated is placed _________. a. b. c. d. at the anode at the cathode at either the anode or cathode in between the anode and the cathode _____ 47. What is the purpose of the electrolyte in a cell used to electrolyze water? a. b. c. d. It reacts with water to produce hydrogen. It reacts with water to produce oxygen. It carries current between the electrodes. It neutralizes the ions produced at the electrodes. _____ 48. Which of the following is true about an electrolytic cell? a. b. c. d. Unit 4 Evaluation It changes electrical energy into chemical energy. It is the type of cell used in electroplating. It uses an electric current to make a nonspontaneous reaction go. all of the above 149 SCIH 032 _____ 49. Which reaction occurs when bromine is added to an aqueous solution of iodide ions? a. b. c. d. 2I- + Br2  I2 + 2BrI2 + 2Br-  Br2 + 2I2I- + 2Br-  I2 + Br2 I2 + Br2  2I- + 2Br- _____ 50. Which metal will react spontaneously with Cu(aq) at 25°C? a. b. c. d. Ag Au Mg Hg Carefully check your answers on this evaluation and make any corrections you feel are necessary. When you are satisfied that you have answered the questions to the best of your ability, transfer your answers to an answer sheet. Please refer to the information sheet that came with your course materials. Unit 4 Evaluation 150 SCIH 032
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Explanation & Answer

Here are the answers, please tell me if you have any problem.

1.
2.
3.
4.

Oxidizing agent
Reducing agent
Oxidation number
Half-reaction

5. Assign oxidation numbers to all the atoms
6. Choose coefficients to make the change in oxidation number
equal 0
7. Write the equation showing ions separately
8. Add the balanced half-reactions to all the atoms.

9. c. Electrons
10.d. loss of electrons
11.a. lead
12.d. oxidation
13. a. Na
14.a. iron is oxidized
15.d. +2
16.b. N = -3, H = +1, Cl = -1
17.c. Chlorine
18.d. no change ...


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