Redox Stability Field Of Natural Water Flashcards
What are comproportionation reactions?
Reactions where an element in two different oxidation states combines to form a product with the element in an intermediate oxidation state.
How do comproportionation reactions relate to disproportionation reactions?
They are simply the reverse of disproportionation reactions.
What are natural waters?
Water obtained from lakes and rivers.
What are the common pH limits of natural waters?
pH = 4 and pH = 9.
What does the redox stability field of natural waters represent?
The region of pH and redox potential in which water is stable towards both oxidation and reduction.
In the redox stability field of natural waters, what does the shaded area depict?
The range of values of E° and pH in which water is neither oxidized nor reduced.
What are the vertical lines in the stability field figure indicative of?
The pH limits at pH 4 and pH 9.
What is the significance of redox potential limits in the stability field?
They define the conditions under which water remains thermodynamically stable.
Fill in the blank: The redox stability field of water indicates that it is stable towards both _______ and _______.
[oxidation] and [reduction].
True or False: The redox stability field of natural waters includes conditions where water can be oxidized.
False.
What factors were not considered when obtaining the curve for the redox stability field of natural waters?
Hydrogen overvoltage and oxygen overvoltage.
What does the curve in the redox stability field plot represent?
Reduction potentials of H+ ions to give H2 and standard oxidation potentials of H2O to give O2 with the change in pH.
What are the pH limits for the stability field area?
pH=4 and pH=9
These limits are shown by vertical lines in the figure.
What do the upper (AB) and lower (CD) sloping lines represent?
Redox potential limits
These lines indicate the boundaries for oxidizing and reducing agents.
What can oxidizing agents above the upper AB line do?
Oxidize H2O to liberate O2
This occurs when their redox potentials are higher than the AB line.
What can reducing agents below the lower CD line do?
Reduce H+ ions to liberate H2
This occurs when their redox potentials are lower than the CD line.
What is the E value threshold for oxidizing H2O to O2?
More than 1.23V - (0.591V) pH
This indicates the necessary redox potential for oxidation.
What is the E value threshold for reducing H+ ions to H2?
More than - (0.591V) pH
This indicates the necessary redox potential for reduction.
How does hydrogen overvoltage and oxygen voltage affect the stability field of water?
Extends the stability field on both upper and lower sides of AB and CD lines
This results in the representation of redox potential limits by broken lines.
Fill in the blank: The stability field of water is represented by _______.
Vertical lines for pH limits and sloping lines for redox potential limits
These lines help to identify the conditions for oxidation and reduction.
