Final answer:
Chemical tests for identifying Ni2+ and Cu2+ involve observing color changes and precipitation when reacting with various substances. For Cu2+, its blue color in solution and redox reactions with metals like zinc or silver are indicative. For Ni2+, its ability to reduce copper ions but not zinc ions can be used for identification.
Step-by-step explanation:
The identification of Ni2+ and Cu2+ ions can be accomplished using different chemical tests that rely on the specific reactivity and color changes associated with these ions in solution. When copper (Cu) wire reacts with nitric acid (HNO3), it produces copper (II) nitrate, nitrogen dioxide (NO2), and water (H2O). The blue color of the copper salts in solution signifies the presence of copper ions due to the arrangement of electrons in their d orbitals.
In another type of redox reaction, placing copper metal in a solution of silver nitrate (AgNO3) will result in the reduction of silver ions and oxidation of copper metal. The solution will turn blue, indicating the presence of Cu2+ ions, while silver will form on the copper surface. In the case of nickel, nickel metal can reduce copper (II) ions, but cannot reduce zinc ions, indicating that it lies between Cu2+ and Zn2+ in the reactivity series, which can be used to predict the spontaneity of redox reactions.