A student intends to prepare 250.0 mL of a 0.250 M copper(II) nitrate solution
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Problem
A student intends to prepare 250.0 mL of a 0.250 M copper(II) nitrate solution. The correct mass of crystalline Cu(NO₃)₂·3H₂O is weighed, transferred to a 250 mL volumetric flask, dissolved, and the flask is brought to volume at the calibration mark. However, while swirling to mix, the student accidentally adds an extra 3.00 mL of distilled water past the calibration mark, resulting in a total solution volume of 253.0 mL.
Respond to the following.
(a) Calculate the number of moles of Cu(NO₃)₂ that the student intended to have in the solution.
(b) Determine the actual molarity of Cu(NO₃)₂ in the 253.0 mL solution.
(c) Compute the percent error between the actual molarity and the target molarity of 0.250 M.
(d) Propose a quantitative method—using only additional solid Cu(NO₃)₂·3H₂O or additional distilled water—to correct the solution so that its molarity is brought precisely to 0.250 M. Justify your method with calculations.