Final answer:
Copper salts generally display a blue color, a characteristic demonstrated by the color change observed when copper ions are dissolved in solution such as in copper sulfate or utilized in compounds like copper phthalocyanine blue in dyes.
Step-by-step explanation:
Copper salts generally have a blue color. This can be exemplified by reactions where copper(II) ions are involved. For example, the reaction of a copper wire in a solution containing silver(I) ions leads to the copper displacing the silver ions, which results in a characteristic blue color in the solution due to the copper ions (Cu2+).
This color change is particularly noticeable with copper (II) sulfate in solution, which has a pale blue or cyan color when white light passes through it, as the copper(II) ions absorb light in the red region of the spectrum. Additionally, compounds like copper phthalocyanine blue utilized in blue dyes further demonstrate the blue coloration associated with copper compounds.