This is a formula for making a chemical, not for a star.
Notes from AndyH: The copper sulfate need not be desiccated, as the ratio takes into effect the 5 moles of water that’s usually attached. Dissolve the copper sulfate into boiling distilled water (~40g/100g water), and add your potassium benzoate to the least amount of boiling distilled water that it will dissolve in. Combine the two solutions. The dark blue color of the copper sulfate solution should turn clear and a blue precipitate of copper benzoate should result. Let the solution settle overnight, decant or siphon off the solution above the copper benzoate, and then wash it with a few more volumes of warm distilled water to remove most of the potassium sulfate created.