Please help me to solve question (1) e,(1)f and (1)g. Also (2) b. 10.00 mL of a

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Please help me to solve question (1) e,(1)f and (1)g. Also (2) b.

10.00 mL of a sample of the alcohol (HOH_2C-CH_2OH, ethylene glycol), is acidified and then oxidized with 10,00 mL of 0.2548 M periodic acid (HIO), to form formaldehyde (H_2C = O) and IO_3^-. The oxidizer, HIO_4 is used here in excess by design. (a) write the oxidation half reaction involving ethylene glycol. (b) Write the reduction half reaction involving periodic acid. (c) Write the overall reaction between ethylene glycol and periodic acid. (d) What is the mole ratio of IO_4 to glycol in the overall reaction? (e) Once the ethylene glycol was completely oxidized with periodic acid, a sufficient amount KI was added to convert a of the un-reacted to IO_4^- to IO_3^-, releasing a quantitative amounts of IO_3^-. Write the oxidation and reduction half reactions and the balanced overall reaction at this stage (e) What is the mole ratio of I_3^- to IO_4^- of this react (f) 2.374 mmol of sodium thiosulfate was required to completely react the produced in (e) returning it to Gamma and to form S_4O_6^-2 in the process). Write the oxidation and reduction half reactions at this stage and follow it by giving the overall reaction. What is the mole ratio of I_3^- to S_2O_3^-2 (g) Calculate the molarity of glycol in the sample analyzed. (a) The pH of a 5.00 mL of a 100-ppm iron(II) is adjusted to pH 4.0 with an appropriate buffer and an excess of 1, 10-phenanthroline was added. An orange-colored complex forms, in which each iron (II) ion is complexed with 1, 10-phenanthroline. The volume of the reaction is made up to 100.00 mL with deionized water. The transmittance of the resulting solution was 37.6% T at 540 nm in 1.2 cm path-length cuvette. the molar a absorptivity of the complex. (Assume that formation constant of the complex is sufficiently large the reaction is complete) (b) 2.50 times 10^-3 M solution of a compound, A, gives the absorbance spectrum curve A shown below. A 5.00 times 10^-3 solution of another compound B, gives absorbance spectrum shown on the same scale; cuvette path-length = 1.00cm. A mixture of these two compounds gives the spectrum labeled 'mixture'. All spectra were obtained using the same cuvette.

Explanation / Answer

1.

(e) Balanced half reactions

oxidation : 2I- --> I2 + 2e-

reduction : IO4- + 2e- --> IO3-

Overall equation : IO4- + 3I- + H2O --> IO3- + I3- + 2OH-

mole ratio of of I3- to IO3- = 1 : 1

(f) Balanced half reactions

oxidation : 2S2O3^2- --> S4O6^2- + e-

reduction : I3- + e- --> 3I-

Overall equation : 2S2O3^2- + I3- --> S4O6^2- + 3I-

moles ratio of I3- to S2O3^2- = 1 : 2

(g) molarity of glycol solution

moles Na2S2O3 reacted with excess I3- = 2.374 mmol

moles I3- reacted = 2.374/2 = 1.187 mmol

moles IO4- initial = 0.2548 M x 10 ml = 2.548 mmol

moles of IO4- reacted with ethylene glycol = 2.548 - 1.187 = 1.361 mmol

molarity of ethylene glycol = 1.361/10 = 0.1361 M

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