<prompt> Answer this question truthfullyWhat is the compound known as iron II sulfate?  <response>: <reason> IronII sulfate is the chemical compound with the formula Fe S O 4. Also known as ferrous sulphate, or copperas, ironII sulfate is most commonly encountered as the blue-green heptahydrate. In its anhydrous, crystalline state, its standard enthalpy of formation is Δ f H solid -928.4 kJ.mol -1 and its standard molar entropy is S solid 107.5 J.K -1.mol -1. 