Chapter 15.4, Problem 40SSC

Interpretation Introduction

Interpretation:

The elements in their standard states on the scale of standard enthalpies of formations are to be described.

Concept introduction:

The standard enthalpy of formation is defined as heat change when one mole of a compound is formed in standard state.

Answer to Problem 40SSC

The standard enthalpies of formation of elements in standard state are assigned zero value.

Explanation of Solution

Standard enthalpy of formation of element is taken as zero. With this zero point all the compounds are assigned enthalpies in positive or negative side.

Conclusion

To make the calculations easy, standard enthalpies of formation of elements in standard state are assigned zero value.