Academic Integrity: tutoring, explanations, and feedback — we don’t complete graded work or submit on a student’s behalf.

Name InstructorW EXPERIMENT 11 OXIDATION-REDUCTION TITRATION Pre-Laboratory Ques

ID: 1038802 • Letter: N

Question

Name InstructorW EXPERIMENT 11 OXIDATION-REDUCTION TITRATION Pre-Laboratory Questions 1. Explain in terms of electron movement what is meant by the term "oxidation." 2. Explain in terms of electron movement what is meant by the term "reduction." 3. Determine the oxidation number for the underlined atomic species. Then indicate if the half- reaction is an oxidation or a reduction. Reagent Oxidation # Product Oxidation Oxidation Reduction Half-Reaction List the color change expected at the equivalence point for each of the possible titrations you might perform in Parts B, C and D. 4. D· ClO" + I'·+1 1,0.-I, + Cl,_ + 311,0 (starch present) l, + s,0z t + s,o_ (starch present). 125 OXIDATION-REDUCTION TTRATION

Explanation / Answer

1. Oxidation in terms of electron moment:

A: Oxidation is a process in which an atom or a group of atoms taking part in a redox reaction would lose 1 or more electrons. The loss of electrons results in the increase of positive charge or decrease of negative charge of the species.

2. Reduction in terms of electron moment:

Reduction is a process in which an atom or a group of atoms taking part in a redox reaction would gain 1 or more electrons. The gain of electrons results in the decrease of positive charge or increase of negative charge of the species.

3.

1. VO21+ (aq) + 2H+ (aq) ---------> VO2+ (aq) + H2O (l)

on reactants side:

VO21+ O= -2, 2O => 2*-2 = -4, let V=x, => x+ (-4) = +1 => x= 5, V= +5

on products side:

VO2+ O= -2, let V=y, => y+ (-2) = +2 => y = 4, V= +4

Change of +5 to +1 is decrease in +ve charge, which based on above definitions is a reduction.

2. 2KIO3(aq) + 6H+ (aq) ---------> I2 (aq) + 2K+ (aq)  + H2O (l)

on reactants side:

2KIO3, O= -2, 3O => 3*-2 = -6, k= +1, let I=x, => 1+ x+(-6) = 0 => x= 5, I = +5

on products side:

it is in elemental form, I2 meaning the oxidation state is 0.

Change of +5 to 0 is decrease in +ve charge, which based on above definitions is a reduction.