Chalcopyrite (cufes2) is an abundant copper mineral that can be converted into elemental copper through the four step process below.
a) calculate the mass of cu in g from 5.40 kg cufes2.
i got 1.87e3g of cu.
b)calculate the mass of cufes2 needed in g to produce 150.0 g cu if the yield for the conversion process is 82%.

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.