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3. To balance (N-7), the reaction needs to be split into two half reactions. The two half reactions are given below. After balancing each half reaction in acidic conditions, combine them and write a balanced reaction for (N-7). S2O3 2- (aq) ? S4O6 2- (aq) I3- (aq) ? I- (aq) 4. The triiodide produced by the first reaction is then consumed by the second one. Use the stoichiometry from the balanced equations in questions 2 and 3, to obtain the conversion factors for the overall reaction stoichiometry for this experiment. Complete the following dimensional analysis with the appropriate mol/mol ratios in the empty (—) positions shown. ( XXXX mol IO3- / L ) ( — ) ( — ) = mol S2O3 2- / L 5. If some of the triiodide you form initially escapes from the titration flask before it reacts with thiosulfate, will the calculated thiosulfate concentration be too low, too high, or not modified by this loss? Support your answer. 6. Using equation (N-5), explain using chemical principles why sodium carbonate is added to the thiosulfate solution. 7. Which quantities in this experiment must be measured quantitatively? Which ones may be measured with less quantitative tools such as a graduate cylinder or centigram balance? 8. Water heated in a clean flask may superheat, that is become hotter than its boiling point without boiling (also discussed in Proj. K: Ksp Determination). Anything added to superheated water may result in a vigorous "bumping" of hot water out of the flask due to the increased surface area available to promote vaporization. This has the potential for producing severe burns. What should be added to the flask of boiling water to prevent bumping?

3. To balance (N-7), the reaction needs to be split into two half reactions. The two half reactions are given below. After balancing each half reaction in acidic conditions, combine them and write a balanced reaction for (N-7).
S2O3 2- (aq) ? S4O6 2- (aq) I3- (aq) ? I- (aq)
4. The triiodide produced by the first reaction is then consumed by the second one. Use the stoichiometry from the balanced equations in questions 2 and 3, to obtain the conversion factors for the overall reaction stoichiometry for this experiment. Complete the following dimensional analysis with the appropriate mol/mol ratios in the empty (—) positions shown.
( XXXX mol IO3- / L ) ( — ) ( — ) = mol S2O3 2- / L
5. If some of the triiodide you form initially escapes from the titration flask before it reacts with thiosulfate, will the calculated thiosulfate concentration be too low, too high, or not modified by this loss? Support your answer.
6. Using equation (N-5), explain using chemical principles why sodium carbonate is added to the thiosulfate solution.
7. Which quantities in this experiment must be measured quantitatively? Which ones may be measured with less quantitative tools such as a graduate cylinder or centigram balance?
8. Water heated in a clean flask may superheat, that is become hotter than its boiling point without boiling (also discussed in Proj. K: Ksp Determination). Anything added to superheated water may result in a vigorous "bumping" of hot water out of the flask due to the increased surface area available to promote vaporization. This has the potential for producing severe burns. What should be added to the flask of boiling water to prevent bumping?

Added by -Scar A.

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