A closed system is completely closed to the outside environment. Every interaction is transmitted inside that closed system.
A measure of kinetic energy of particle motion within a substance is temperature.
Yes. If this is the balanced equation:
AlCl3 + 3Na —— 3NaCl + Al
then Al was reduced from a 3+ oxidation (to neutralize the 3- from the chlorine) to a 0 oxidation (elemental ground state).
3Fe + 4H2O (yields) Fe3O4 + 4H2
