i have noticed in the lab, that a small amount of blue CuSO4 crystals (like 0.5g or even smaller than that) when dissolved in water makes it a greyish-white opaque colour. when u go on adding more and more copper sulphate crystals and dissolving them in the water, the solution becomes more and more aqua blue and transparent in colour.
why does this happen? does it have anything to do with the way the CuSO4 crystal is structured?
i am using this in a physics experiment. i want to know if a solution of very low concentration CuSO4 (that is more opaque in colour) will allow more light to pass through it than a solution with a higher concentration of CuSO4 (that is clear blue in colour) or not?
2007-01-17 05:09:46 · 2 answers · asked by amandac 3 in Science & Mathematics ➔ Chemistry
Great observation! What's going on is that the CuSO4 is dissociating into Cu2+ and SO42- ions. The sulfate ions are colorless, but the Cu2+ ions give the solution the color you are seeing. This is common with most metal ions, because of something caled band theory (ask a chemist, its actually pretty cool but I don't remember it well enough to explain it). And yes, you are absolutely right about measuring the concentration by the color. This is done with an instrument called a spectrophotometer, which measures the amount of light of a specific wavelength passes through a sample, and can be used to determine the concentration of most ions in solution. Good luck on your physics experiment.
2007-01-17 05:24:18 · answer #1 · answered by Anonymous · 0⤊ 0⤋
I just tried it and my solutions are always clear blue.
2007-01-17 13:27:08 · answer #2 · answered by deflagrated 4 · 0⤊ 0⤋