1 C118: TWO OXIDATION STATES OF VANADIUM 25 POINTS NAME: LAB PARTNER: Data: (4 pts. for thorough observations) Be sure to record your observations for each of the reactions that you have set up after three minutes. Indicate if a reaction has taken place. How will you know? Indicate if heat was required for the reaction to occur; record your observations for each solution before and after it was heated. Reduction of VO2+ Reducing Agent Observations H2O Br- HNO2 Fe2+ H2SO3 H2C2O42Oxidation of VO2+ Oxidizing Agent Observations SO4 2- Fe3+ NO3- Br2 H2O231. (1 pt.) In this experiment you are using a series of reactions and observations to determine the cell potential for the following reaction. VO2+ + 2 H+ + e- → VO2+ + H2O E0 = x Give the colors of VO2+ and VO2+. 2. (6 pts.) a) Write the overall balanced redox reactions for VO2+ with various reducing agents (H2O, Br-, HNO2, Fe2+, H2SO3, H2C2O4). b) Give the experimental observation and state whether a spontaneous reaction occurred. c) For each balanced reaction use the experimental observation to find a range for the value of x. (For example, x > 0.25 V) 3. (1 pt.) What is the range for x determined from the reactions with reducing agents?4 4. (2 pts.) Write the overall reaction for the oxidation of VO2+. How does the standard cell potential for this reaction relate to the standard cell potential (x) for the reduction of VO2+? 5. (6 pts.) a) Write the overall balanced reactions for VO2+ with various oxidizing agents (SO42-, Fe3+, NO3-, Br2, H2O2) b) Give the experimental observation and state whether a spontaneous reaction occurred. c) For each balanced reaction use the experimental observation to find a range for the value of x. (For example, x > 0.25 V) 6. (1 pt.) What is the range for x determined from the reactions with oxidizing agents? 7. (1 pt.) What is the range for x determined from all reactions?58. (3 pts.) The literature value of the standard cell potential for VO2+ + 2 H+ + e- → VO2+ + H2O is 0.991 V. Evaluate the accuracy of this method for determining a standard cell potential and comment on sources of
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