Chapter 17, Problem 68A

Interpretation Introduction

Interpretation: The standard heat of formation for a free element in its standard state is to be found.

Concept Introduction: The standard enthalpy of formation is the amount of energy released or consumed when one mole of a substance is formed under standard conditions from its pure element.

Answer to Problem 68A

The standard heat of formation for a free element in its standard state is zero.

Explanation of Solution

The enthalpy of formation for an element in its elemental state will always be zero as it does not require any energy to form a free element as it is made from itself.

Conclusion

Thus, the standard heat of formation for a free element in its standard state is zero.