In Lab 9, students performed acid-base titrations. Redox reactions can also be used in titrations. An example is the titration of ascorbic acid (H C H O ) in lemon juice using triiodide (I ). A starch indicator will turn the solution blue-black at the endpoint. The half-reactions involved are shown below. (a) What is the net redox reaction that occurs? (Use the lowest possible coefficients. Omit states-of-matter from your answer.) Pad [removed] (b) What is the stoichiometry of H C H O to I ? [removed]3:1 [removed]8:3 [removed]2:1 [removed]1:1 [removed]1:2 [removed]3:8 [removed]1:3 (c) Use the data given below to determine the amount of ascorbic acid in lemon juice. ( The recommended daily allowance of ascorbic acid (Vitamin C) is 90 mg.) Determine the errors (if any) with each galvanic cell set-up when the anode is on the left. (Select all that apply.) [removed]There is nothing wrong with this diagram. [removed]The electrodes are in the wrong solution. [removed]The electrons are traveling the wrong direction down the wire. [removed]The salt bridge ions are migrating to the incorrect electrode. [removed]The electrons are traveling through the salt bridge. [removed]The electrodes and solutions are in the wrong compartment. [removed]There is nothing wrong with this diagram. [removed]The electrodes are in the wrong solution. [removed]The electrons are traveling the wrong direction down the wire. [removed]The salt bridge ions are migrating to the incorrect electrode. [removed]The electrons are traveling through the salt bridge. [removed]The electrodes and solutions are in the wrong compartment. [removed]There is nothing wrong with this diagram. [removed]The electrodes are in the wrong solution. [removed]The electrons are traveling the wrong direction down the wire. [removed]The salt bridge ions are migrating to the incorrect electrode. [removed]The electrons are traveling through the salt bridge. [removed]The electrodes and solutions are in the wrong compartment. [removed]There is nothing wrong with this diagram. [removed]The electrodes are in the wrong solution. [removed]The electrons are traveling the wrong direction down the w
ire. [removed]The salt bridge ions are migrating to the incorrect electrode. [removed]The electrons are traveling through the salt bridge. [removed]The electrodes and solutions are in the wrong compartment. [removed]There is nothing wrong with this diagram. [removed]The electrodes are in the wrong solution. [removed]The electrons are traveling the wrong direction down the wire. [removed]The salt bridge ions are migrating to the incorrect electrode. [removed]The electrons are traveling through the salt bridge. [removed]The electrodes and solutions are in the wrong compartment. Consider your experimental results from part A of this lab. Suppose your strongest reducing agent were added to your strongest oxidizing agent. (Use the lowest possible coefficients. Omit states-of-matter from your answers.) (a) Write the half-reaction for your strongest reducing agent. Pad Mg → Mg + 2e [removed] Correct. (b) Write the half-reaction for your strongest oxidizing agent. Pad MnO + 8H + 5e → Mn +4H O [removed] Correct. (c) Note the number of electrons in each half reaction. In order to balance the number of electrons lost and gained, the oxidation half-reaction must be multiplied by and the reduction half-reaction must be multiplied by (d) Write the net redox reaction. Pad Assemble a battery, represented by the diagram below with the cathode in compartment A, with Sn /Sn and Cu /Cu couples in which the voltage reads positive. (Use the . Use the lowest possible coefficients. Omit states-of-matter from your answer.) (a) What half-reaction occurs in compartment A? Pad Sn → Sn +2e [removed] Your answer contains an ambiguous or incomplete reaction equation. Check all the components on the reactant-side of the equation. Check all the components on the product-side of the equation. (b) What half-reaction occurs in compartment B? Pad Cu +2e → Cu [removed] Your answer contains an ambiguous or incomplete reaction equation. Check all the components on the reactant-side of the equation. Check all the components on the product-side of the equation. (c) Write the net redox reaction. Pad Sn + Cu → Sn + Cu [removed] Correct. [removed]