What is the alternate form of caf2+h2so+157.7kj→caso4+2hf

CaF₂+H₂SO₄ → CaSO₄+2HF     ΔH = +157.7KJ

Explanation:

Energy changes in chemical reactions is one of the most important issues in thermodynamics  especially the enthalpy of reaction (ΔHrxn)

(ΔHrxn) can be defined as  the difference between the total enthalpy of the products and the total enthalpy of the reactants of a certain reaction.If ΔH<0  for an exothermic reaction (i.e. heat flows from a system to its surroundings) or in other words,  the enthalpy of the products is less than the enthalpy of the reactantsWhile, ΔH>0  for an endothermic reaction (i.e. heat flows from the surroundings to a system) that means the enthalpy of the products is greater than the enthalpy of the reactants.In this example    

           CaF₂+H₂SO₄+157.7KJ → CaSO₄+2HF

heat flows from the surroundings to a system and so ΔH>0

which can be expressed in alternate form as following

CaF₂+H₂SO₄ → CaSO₄+2HF     ΔH = +157.7KJ