Neco 2018 Chemistry Question 5

Practice objective / multiple choice question 5 from the 2018 Neco Chemistry examination.

Neco 2018 Chemistry Objective / Multiple Choice Hard Difficulty
Question 5 NECO • 2018 • CHEMISTRY • objective

A steel pipe exposed to seawater experiences a corrosion current density of 2.5\,μA\,cm\(^{-2}\). The external surface area of the pipe is 1500\,cm\(^{2}\). (a) Calculate the corrosion rate in mm per year using the formula \(CR = \dfrac{0.00327\,I_{corr}\,EW}{\rho}\), where \(I_{corr}\) is in μA\,cm\(^{-2}\), \(EW\) (equivalent weight of Fe) = 27.9\,g\,eq\(^{-1}\), and \(\rho\) (density of Fe) = 7.87\,g\,cm\(^{-3}\). (b) If a zinc coating reduces the corrosion current density to 0.4\,μA\,cm\(^{-2}\), what is the new corrosion rate? (c) Determine the percentage reduction in mass loss per year due to the coating.

Answer Options

A. a) 0.035 mm/yr; b) 0.0058 mm/yr; c) ≈78 % reduction in mass loss
B. a) 0.025 mm/yr; b) 0.0039 mm/yr; c) ≈86 % reduction in mass loss
C. a) 0.031 mm/yr; b) 0.0042 mm/yr; c) ≈82 % reduction in mass loss
Correct Answer D. a) 0.029 mm/yr; b) 0.0046 mm/yr; c) ≈84 % reduction in mass loss
Correct Answer
D
Correct Option:
a) 0.029 mm/yr; b) 0.0046 mm/yr; c) ≈84 % reduction in mass loss

About This Question

This is Neco 2018 Chemistry Question 5. It is one of the objective questions from the 2018 Neco Chemistry examination.

Difficulty level: Hard .

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