Chapter 12, Problem 111A

Interpretation Introduction

Interpretation:

The reason for liquid iodine to not usually visible when iodine crystals are heated in the open air must be explained.

Concept introduction:

Iodine is a substance which undergoes sublimation when heated.

Answer to Problem 111A

Liquid iodine is not generally visible as solid iodine is directly converted to iodine vapor in the process of sublimation.

Explanation of Solution

Van der Waals forces between two iodine atoms are very low. So intermolecular forces are weak in iodine. Thus when iodine is heated intermolecular force decreases sharply and it is directly converted to iodine vapor without attainment of liquid state. This process is known as sublimation.

Conclusion

Liquid iodine is not visible as iodine has high tendency for sublimation.