A wastewater sample collected from a metal-finishing facility is suspected to contain…
CHEMISTRY · Multi-part · A Level · Chemistry · Acids and bases · Acids and bases
Problem
A wastewater sample collected from a metal-finishing facility is suspected to contain dissolved calcium hydroxide at 25 °C. A field technician measures the pH of the water to be 12.45. Environmental regulations require that the hydroxide-ion concentration in discharge water not exceed 1.0×10−3M.
(a) Determine the hydroxide-ion concentration in the wastewater sample.
(b) Calculate the molar concentration of Ca(OH)2 responsible for the measured pH.
(c) Using your result from part (a), state whether the wastewater sample violates the regulatory limit and support your answer quantitatively.
(d) If the facility can only dilute the wastewater with pure water, calculate the minimum volume of pure water that must be added per liter of wastewater so that the final hydroxide-ion concentration meets the regulatory limit.