Difference between calcium sulfide and calcium sulfate.

Calcium sulfide is a chemical compound having formula CaS. While  Calcium sulfide is inorganic compound g fomlaCaSO4.

Explanation:

calcium sulfide is use in  preparation of  hydrogen sulfide, luminous pain and as a depilatory in cosmetics while  calcium sulfate is used as desiccant. calcium sulfides is  white material crystallizes in cubes like rock salt while calcium sulfate has three different crystalized forms known as hemihydrate (CaSO4⋅12H2O) , anhydrate (CaSO4) and as  gypsum (CaSO4⋅2H2O). hope this explanation will be helpful for you

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.