Redox Titrimetric Methods Flashcards

1
Q

Give the three most commonly oxiding titrants in redox methods.

A

Permanganate, dichromate, iodine

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2
Q

Give the two common reducing titrants in redox methods

A

Fe2+ and thiosulfate

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3
Q

The reaction of permanganate is in ___ medium.

A

Acidic

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4
Q

The reaction of permanganate is in ___ medium.

A

Acidic

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5
Q

In permanganimetry, the titration does not require an indicator since the oxidized (violet) and reduced (colorless) forms of titrant (MnO4-) differ in color. True or false

A

True

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6
Q

KMnO4 can be standardized in acidic medium using which of the ff.
A. Pure Fe wire
B. Sodium oxalate
C. Arsenic trioxide

A

ABC

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7
Q

At the beginning of the titration, the violet color of MnO4- persists for several seconds before it disappears. As Mn2+ is formed, the reaction proceeds more rapidly as a result of ______.

A

Autocatalysis

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8
Q

What is the endpoint of permanganimetry when an excess MnO4- has been added.

A

Faint pink color

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9
Q

n of C2O4^2-

A

2

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10
Q

n of MnO4-

A

5

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11
Q

Common oxidizing titrant weaker than permanganate, dichromate, and cerium

A

Iodine

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12
Q

Solutions of iodine lack ____ so they are standardized regularly

A

Stability

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13
Q

2 types of titrations that involves iodine. Which of the two is commonly performed?

A

Iodometry and Iodimetry.
Iodometry

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14
Q

________ refers to the direct use of iodine while ________ refers to the generation of iodine.

A

Iodometry, Iodometry

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15
Q

Process that involves the titration of an analyte (reducing agent) with solutions of iodine (oxidizing agent)

A

Iodimetry

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16
Q

Process of indirect determination of an analyte (oxidizing agent) shich is added to excess iodide to produce iodine, titrated with standard thisoulfate solution.

17
Q

Forms when the molecular iodine complexes with iodine. It also forms a dark blue complex with the amylose units of starch

A

Triiodide ion (I-)

18
Q

Triiodide io decomposes in solutions when the concentration of iodine is high.Thus ____ is added before nearing the endpoint, and addition of _____ is resumed until the end point is reached.

A

Starch, titrant (thiosulfate)

19
Q

Solutions of ____ can be used in place of KMnO4- in most procedures as it’s also a strong oxidizing agent.

20
Q

Solutions of Ce4+ can be prepared from the primary standard _____ in 1M H2S2O4

A

Diammonium hexanitratoacerate (IV)
(NH4)2[Ce(NO3)6]

21
Q

In oxidation with cerium, Ce4+ prepared from other salts such as Ce(OH)4 must be standardized using ____

A

Iron or sodium oxalate

22
Q

Ce4+ is _____ (in acid) and Ce3+ is ____. Yet cerium can’t serve as it’s own indicator because the color is not so distinct.

A

yellow, colorless

23
Q

These are used to visually detect end points during redox titrations.

A

Redox indicators

24
Q

What is the suitable indicator for Ce4+ when the primary standard used is Fe2+

A

Tris (1,10- phenanthroline) iron or ferroin

25
A relatively strong oxidizing agent, though weaker compared to permanganate and cerium
Potassium dichromate
26
Use of K2Cr2O7 as ______ is limited only to analytes that are highly oxidizable.
Oxidant
27
Which of the ff. are the advantages of using dichromate? A. availability as primary standard B. Long term stability of it's solution
AB
28
The color of Cr2O7^2- is ______ and complexes of Cr3+ range from ______ to ______.
Orange, green to violet
29
True lr false. Dichromate can serve as it's own indicator.
False
30
_______ whose oxidized form is ______ and reduced form is _____, giver very distict end point with Cr2O7^2-.
Diphenylamine sulfonic acid (C12H11NO3S) Red-violet Colorless
31
____ proposed ____ that relates the reduction potential (E) of an electrochemical reaction to the standard electrode potential (E°), temperature and activities (or concentrations) of the chemical species undergoing reduction and oxidation
Walther Nernst, Nernst Equation
32
By plotting the reduction potential of an electrochemical cell against the volume of titrant, ____ can be generated.
Titration curve