Which of the following conditions MUST be true for the entropy of a pure solid to be zero?
a) T must be 0 K
b) The solid must be crystalline and not amorphous
c)the solid must be perfectly ordered
d) the solid form must be an element
T=0K
if
S=0 (s is entropy)
It can be more than one of these choices, its a "check all that apply" question. Are there any other options that must apply for S=0??
See here:
http://en.wikipedia.org/wiki/Residual_entropy
To determine which condition(s) must be true for the entropy of a pure solid to be zero, let's analyze the options:
a) T must be 0 K (Kelvin)
The entropy of a substance is defined as zero only at absolute zero (0 K) temperature. At this temperature, molecules lose all their thermal motion, resulting in a perfectly ordered arrangement, and hence, zero entropy. However, this condition is quite extreme and not generally encountered in practical situations.
b) The solid must be crystalline and not amorphous
Crystals are highly ordered structures with a regular pattern of particles, which leads to low entropy compared to amorphous substances. In amorphous solids, the particles lack long-range order, resulting in higher entropy. Therefore, for the entropy of a pure solid to be as close to zero as possible, it would ideally be in a crystalline form.
c) The solid must be perfectly ordered
Perfectly ordered solids have a specific arrangement of particles, resulting in low entropy. Disorder or randomness in the particle arrangement increases entropy. Therefore, the entropy of a pure solid would approach zero if it is perfectly ordered.
d) The solid form must be an element
Entropy is generally lower for pure substances (elements) compared to compounds. Elements have simpler atomic arrangements and thus exhibit lower entropy.
Considering the above explanations, the correct conditions for the entropy of a pure solid to be zero would be options b) The solid must be crystalline and not amorphous and c) The solid must be perfectly ordered. While a) T must be 0 K and d) the solid form must be an element contribute to lower entropy, they are not mandatory requirements for the entropy to be exactly zero.