Using Hess’s law, what is the standard enthalpy of formation of manganese (II) oxide, MnO(s)?

see explanation

Explanation:

By definition, the Standard Heat of Formation (ΔH°(f)) is the heat gained or lost on formation of a molecular substance from its basic elements in their standard state (25°C, 1atm).

For MnO(s) and table of Standard Thermodynamic Properties, the standard state for manganese is Mn°(s) and oxygen O₂(g) which combine to form standard state manganese(II) oxide (MnO(s)) as follows:

Mn°(s) + 1/2O₂(g) => MnO(s); ΔH°(f) = -384.9 Kj/mole

nacl or sodium chloride is an ionic compound. this is because an ionic compound pertains to a compound that consists of positively and negatively charged ions. in this case, na (sodium) has a tendency to lose one electron when it reacts with with other atoms, so the resulting sodium ion contains 11 protons and 10 electrons, thus making it positively charged (na+), when chlorine reacts, it usually gains one electron to form an ion called chloride, thus making it negatively charged ( since the ions are oppositely charged, they attract.

your answer is c) plasma

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