Which of the following has a standard enthalpy of formation value of zero at 25 degrees C and 1.0 atm

A. Fe(s)
B. Fe2O3(s)
C. FeSO4(s)
D. FeSO4(aq)
E. FeS3(s)

and what is enthalpy or how do you find it

All elements have a delta Hf of zero at 1.0 atm and 25o C.

So I need to find the Hf of each of those equations

Absolutely not.

All ELEMENTS have a standard heat of formation of zero at 1.0 atom and 25 degrees C. Which of the 5 answers listed is an ELEMENT (the other four are, of course, compounds).

Fe(s) is an element right

yes.

Fe, all other answers are compounds so they can not have an enthalpy of 0 at 25 C.

To determine which of the given substances has a standard enthalpy of formation value of zero at 25 degrees C and 1.0 atm, we need to understand what standard enthalpy of formation is.

Enthalpy is a thermodynamic property that measures the heat content of a substance or system. It is denoted by the symbol "H." The standard enthalpy of formation (ΔHf°) is the change in enthalpy that occurs when one mole of a compound is formed from its elements in their standard states under standard conditions.

Standard conditions typically refer to 25 degrees Celsius (or 298.15 Kelvin) and 1.0 atmosphere (1.0 atm) of pressure.

To find or calculate the standard enthalpy of formation, we usually refer to published tables or databases that provide the values for various compounds.

Now, let's examine each option provided to determine which has a standard enthalpy of formation value of zero:

A. Fe(s) - This represents solid iron. The standard enthalpy of formation for solid iron is not zero.

B. Fe2O3(s) - This represents solid iron(III) oxide, also known as rust. The standard enthalpy of formation for solid iron(III) oxide is not zero.

C. FeSO4(s) - This represents solid iron(II) sulfate. The standard enthalpy of formation for solid iron(II) sulfate is not zero.

D. FeSO4(aq) - This represents iron(II) sulfate in aqueous solution. Since standard enthalpy of formation values typically refer to compounds in their standard states (solid or gaseous), the standard enthalpy of formation for FeSO4(aq) is not zero.

E. FeS3(s) - This represents solid iron(III) sulfide. The standard enthalpy of formation for solid iron(III) sulfide is not zero.

None of the options provided have a standard enthalpy of formation value of zero.