Write an equation that expresses the law of thermodynamics in terms of heat and work

The first law of thermodynamics is a version of the law of conservation of energy, adapted for thermodynamic systems.The first law is often formulated by stating that the change in the internal energy of a closed system is equal to the amount of heat supplied to the system, minus the amount of work done by the system on its surroundings.Equivalently, perpetual motion machines of the first kind are impossible.

Therefore when aluminum foil is put into the copper salt solution, aluminum atoms on the surface of the foil (in contact with the solution) reacts and takes the place of copper(II) ions in the solution (it now becomes aluminum chloride solution). That is why the blue solution becomes colorless.