the goal of the exercise was to dry acetone.
old, blue CuSO4 was placed in a flask an heated to 200-250°C. strangely the
powder did not become white like maybe two years ago, but grey!
acetone was added and the thing stirred with moisture protection for some hours.
the undissolved powder did not become noticeably more blue. acetone was distilled
off and in order to test the CuSO4, water was added to the residue. result: a _green_
solution (!?!?). only after multiple decanting and refilling with water
did the water finally get a blue colour!
any explanations???