Interpretation:
The value of pH needs to be calculated if voltage is
Concept introduction:
The pH is the negative logarithm of hydrogen ion concentration. Therefore,
Nernst equation is written as follows:
Here, R represents gas constant, T represents temperature, n represents number of electron, F represents Faraday’s constant,
Answer to Problem 62QAP
At voltage
Explanation of Solution
Balance the reaction as follows:
Consider
Reduction:
Oxidation:
Atom balance as follows:
One nitrogen each side.
Hence, no adjustment is required.
Total oxidation number-
Add electrons: Oxidation number for N goes from +5 to +2. It is reduced by 3. Add three electrons to reactant side.
Balance charge: reactants
Products: 0, in acidic medium add
Balance hydrogen atom:
Reactant contains 4 H and product contains 0 H. To balance add
Balance reaction is as follows:
Atom balance as follows:
One sulphur each side. Hence, no adjustment is required.
Total oxidation number-
Add electrons: Oxidation number for S increases from +4 to +6. It is increased by 2. Add two electrons to product side.
Balance charge: Products
In acidic medium add
Balance hydrogen atom:
Reactant contains 0 H and product contains 4 H. To balance, add
Balance reaction is as follows:
Multiply equation (1) by 2 and equation (2) by 3 and add the resulting equation.
Calculate
Use Nernst equation to calculate reaction quotient ( Q) as follows:
Nernst equation is given below.
Here, R represents gas constant, T represents temperature, n represents number of electron, F represents Faraday’s constant,
Here,
Calculate concentration of
Given, pressure of all gases is
Calculate pH as follows:
Therefore, at voltage
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Chapter 21 Solutions
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