when is the entropy of a substance said to be zero
Third law of thermodynamics At absolute zero (zero kelvin) the system must be in a state with the minimum possible energy. Entropy is related to the number of accessible microstates, and there is typically one unique state (called the ground state) with minimum energy.[1] In such a case, the entropy at absolute zero will be exactly zero. If the system does not have a well-defined order (if its order is glassy, for example), then there may remain some finite entropy as the system is brought to very low temperatures, either because the system becomes locked into a configuration with non-minimal energy or because the minimum energy state is non-unique. The constant value is called the residual entropy of the system.[2]
Splenda The energy content of a single-serving (1 g packet) of Splenda is 3.36 kcal, which is 31% of a single-serving (2.8 g packet) of granulated sugar (10.8 kcal).[9] In the United States, it is legally labelled "zero calories";[9] U.S. FDA regulations allow this "if the food contains less than 5 Calories per reference amount customarily consumed and per labeled serving".[10] Further, Splenda contains a relatively small amount of sucralose, little of which is metabolized; virtually all of Splenda's caloric content derives from the dextrose or highly fluffed maltodextrin "bulking agents" that give Splenda its volume. Like other carbohydrates, dextrose and maltodextrin have 3.75 kcal per gram.