⟵ 06 Destructive Oxidation (Engineering Notes) · Contents · 06 Destructive Oxidation (Answer Key) ⟶
Destructive Oxidation: Problem Set
“These are only provided to reinforce understanding. The Engineering Notes contain some of the information that will be required. Make sure to employ dimensional analysis for all unit conversions.”
Level 1 - Conceptual Mastery
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What is the difference between transactional oxidation and destructive oxidation? Why is the formation of NaCl considered transactional while the rusting of iron is destructive?
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The chapter states that oxidation does not distinguish between biology and metallurgy. Explain what this means and why it creates a dilemma for water treatment.
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Four requirements must be present for electrochemical corrosion to occur in water. Name all four and explain why removing any single one stops the reaction.
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In one sentence, explain the temperature paradox: why can corrosion get worse as water warms from 70°F to 120°F even though oxygen solubility decreases?
Level 2 - Applied Thinking
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Oxygen solubility is approximately 8.3 mg/L at 77°F and 4.4 mg/L at 140°F. Assuming linear behavior, estimate the solubility at 100°F. (Note: actual solubility follows a curve - this question uses linear approximation for simplicity.)
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Using the Arrhenius rule of thumb (rate doubles per 10°C rise), calculate the approximate kinetic rate multiplier from 20°C to 50°C.
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The simplified rust reaction is: 4Fe + 3O₂ → 2Fe₂O₃. To produce 10 pounds of rust (Fe₂O₃), how many pounds of iron must be destroyed? (Fe = 55.8, O = 16, Fe₂O₃ = 159.6 g/mol)
Level 3 - System Integration
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Two cooling towers run the same pH and conductivity. Tower A reads ORP of +650 mV; Tower B reads +200 mV. Which tower has stronger oxidizing pressure? Which is more likely to suppress biofilm? Which poses a greater corrosion risk to exposed metals?
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A deaerator normally heats boiler feedwater to 220°F, removing nearly all oxygen. The steam valve fails and feedwater drops to 140°F. If the system flows 50,000 lb/hr, how many pounds of dissolved oxygen per hour are now entering the boiler? Assume the feedwater is exposed to air and reaches approximately air-saturated dissolved oxygen at 140°F.
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The chapter says oxygen is not the strongest oxidant but has two advantages no applied oxidant can match. Name those advantages, and explain why they make oxygen the most persistent corrosion threat in industrial water systems.
Problem notes
Each problem as its own linked note.
6.1 · 6.2 · 6.3 · 6.4 · 6.5 · 6.6 · 6.7 · 6.8 · 6.9 · 6.10
⟵ 06 Destructive Oxidation (Engineering Notes) · Contents · 06 Destructive Oxidation (Answer Key) ⟶