The chemical equation CuS + 4HNO3 -> Cu(NO3)2 + 3H2O + 4NO2

  1. Detailed information about the equation:

    • The equation above describes the reaction process between copper(I) sulfide (CuS) and nitric acid (HNO3), forming copper(II) nitrate (Cu(NO3)2), water (H2O), and nitrogen dioxide (NO2).
    • The equation is balanced, which means the number of atoms of each element on both sides of the reaction is equal.
    • In the equation, CuS and HNO3 are the reactants, while Cu(NO3)2, H2O and NO2 are the reaction products.

  2. Reaction conditions:

    • The reaction usually occurs at room temperature.
    • HNO3 must be in a concentrated state or a concentrated solution.
    • There must be sufficient HNO3 for CuS to completely react.

  3. The reaction process:

    • During the reaction process, CuS will react with HNO3.
    • CuS will be oxidized to Cu(NO3)2, while HNO3 is reduced to NO2.
    • This process also produces H2O as a by-product.

  4. Observable phenomena:

    • When CuS is added to the HNO3 solution, initially, you can see brown gas bubbles (NO2) escaping and the solution gradually turns blue (due to Cu(NO3)2).
    • After the reaction ends, there are no solids left and the solution completely turns blue.

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