Question 373Steam Plants - Assistant Engineer

The correct answer is D) pure and treated to a pH value of 10.5 to 11.0. Ferrous sulfate is more soluble in boiler water when the pH value is high, typically between 10.5 and 11.0. This is because the higher pH value, which indicates a more alkaline environment, helps keep the ferrous sulfate in solution. Maintaining the boiler water at this pH range helps prevent the precipitation of ferrous sulfate, which can lead to scaling and corrosion issues in the boiler system. The other answer choices are incorrect because: A) a pure boiler water with a zero pH value would be highly acidic, which is not desirable; B) a pH of 4.0 to 4.5 would be too low and promote the precipitation of ferrous sulfate; and C) a neutral pH of 7.0 would not be optimal for keeping ferrous sulfate in solution.