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Electrochemistry Review. 10. Which is a very strong reducing agent?. MnO 4 - H + H 2 Na Na +. 10. By definition, the reduction potential for this species is equal to zero. MnO 4 - H + H 2 Na Na +. 10. This is a very strong oxidizing agent. MnO 4 - H + H 2 Na Na +. 10.
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10 Which is a very strong reducing agent? • MnO4- • H+ • H2 • Na • Na+
10 By definition, the reduction potential for this species is equal to zero. • MnO4- • H+ • H2 • Na • Na+
10 This is a very strong oxidizing agent. • MnO4- • H+ • H2 • Na • Na+
10 How many electrons are transferred in the following reaction:MnO4- + Cr + 2H2O MnO2 + Cr3+ + 4 OH- • 1 • 2 • 3 • 4 • 0
10 In which of the following molecules does hydrogen have an oxidation state of -1? • H2O • NH3 • CaH2 • CH4 • H2
10 When solid copper shavings are placed in a solution of dilute HNO3, Cu2+ ions appear and NO gas bubbles form. Which of the following has occurred? • Cu has been oxidized by H+ • Cu has been oxidized by NO3- • Cu has been reduced by NO3- • NO3- has been oxidized by H+ • NO3- has been reduced by H+
10 The half reaction at the anode of a galvanic cell is as follows:Zn (s) Zn2+ + 2e-What is the maximum charge, in coulombs, that can be delivered by a cell with an anode composed of 6.54 g of zinc? • 4820 coulombs • 9650 coulombs • 19300 coulombs • 38600 coulombs • 48200 coulombs
10 Ni(s) + Cu2+ Ni2+ + Cu(s)The reaction above takes place in a galvanic cell. If the initial concentration of Ni2+ is increased while the initial concentration of Cu2+ remains the same, what will be the effect on Q and E? • Q and E will increase • Q and E will decrease • Q will increase and E will decrease • Q will decrease and E will increase • Q and E will not change
10 Look up the reduction potentials for Cu2+, Zn2+, and Mn2+ . Which of the following reactions will occur spontaneously? • Mn2+ + Cu Mn + Cu2+ • Mn2+ + Zn Mn + Zn2+ • Zn2+ + Cu Zn + Cu2+ • Zn2+ + Mn Zn + Mn2+ • Cu2+ + Zn2+ Cu + Zn
10 Which of the following statements is true for the following reaction taking place under standard conditions?Al(s) + Cr3+ Al3+ + Cr(s) • E = 2.40 V, and the reaction is not spontaneous • E = 0.92 V, and the reaction is spontaneous • E = -0.92 V, and the reaction is not spontaneous • E = -0.92 V, and the reaction is spontaneous • E = -2.40 V, and the reaction is not spontaneous
10 What is the reaction potential for the following reaction?Fe2+ + Cu Fe + Cu2+ • -0.7 V • -0.1 V • 0.1 V • 0.7 V • 1.4 V
An electrochemical cell was created by placing a zinc electrode in a 1.00 M solution of ZnSO4 and placing a copper electrode in a 1.00 M solution of CuSO4. The two compartments are connected by a salt bridge, and the following reaction occurred at 25oC. Zn(s) + Cu2+ Zn2+ + Cu(s) • What is the standard potential for the cell? • How much work can the cell do? • What is the value of Keq for the reaction? • At a certain point in the progress of the reaction, [Cu2+] drops to 0.10 M and [Zn2+] increases to 1.90 M. What is the cell potential at this point?
An 800 mL sample of 0.800 M Ag+ solution was electrolyzed, resulting in the formation of solid silver and oxygen gas. The solution was subjected to a current of 2.00 A for 10.0 minutes. The solution became progressively more acidic as the reaction progressed. • Write the two half-reactions that occur, stating which takes place at the anode and which the cathode. • If the oxygen gas produced in the electrolysis was collected at STP, what was its volume? • What was the mass of solid silver produced in the electrolysis? • If the solution was neutral at the start of the electrolysis, what was the pH of the solution when the process was complete?
Sr(s) + Mg2+< -- > Sr2+ + Mg(s)Consider the reaction above that occurs at 25oC. All reactants and products are in their standard states. The value of Keq for the reaction is 4.2 x 1017 at 25o C. • Predict the sign of the standard cell potential for a cell based on the reaction. Explain your prediction. • Identify the oxidizing agent for the spontaneous reaction. • If the reaction were carried out at 60oC instead of 25oC, how would the cell potential change? Justify your answer. • How would the cell potential change if the reaction were carried out at 25oC with a 1.0 M solution of Mg(NO3)2 and a 0.10 M solution of Sr(NO3)2 ? Explain. • When the cell described above reaches equilibrium, what is the cell potential?