According to Chemguide, the Kw of a sample is simply the concentration of hydronium ions multiplied by the concentration of hydroxide ions. In most samples tested at room temperature, the resulting value for Kw is 1.00 x 10-14 mol^2 dm^-6. This means that the pH of even pure water changes with its temperature. Chemguide states that water only retains a neutral pH of 7 at a certain temperature.
Complex ions can identify other electronic pairs replace water molecules which surround the cation. Chemguide(2003) indicates compounds have colours because they absorb lights, such as gamma rays, X-rays, infra-red rays, radio waves, etc. It shows as figure 1 (Chemguide 2003).
Chemguide states that all water molecules act as either a very strong acid or an extremely strong base. The water molecules ionize into these forms at any time. Acting as a base, one water molecule accepts a hydrogen atom from another molecule to form the positively charged hydronium ion, known as H+, and the negatively charged hydroxide ion, known as OH-. Chemguide notes that this process happens in extremely small quantities and in all types of water.
Therefore, when the sunlight pass the copper (II) sulphate solution, red region of the spectrum is absorbed, hence, hcopper (II) sulphate solution will appear cyan, show as figure 2 (Chemguide 2003).