Question

Predict the sign of assys for each of the following pro-cesses:

(a) gaseous H2 reacts with liquid palmitoleic acid (C16H30O2, unsaturated fatty acid) to form liquid palmitic acid (C16H32O, saturated fatty acid).
(b) liquid palmitic acid solidifies at 1 °c to solid palmitic acid.
(c) silver chloride precipitates upon mixing agnos(Ag) and nack(Ag).
(d) gaseous Hz dissociates in an electric arc to form gaseous H atoms (used in atomic hydrogen welding).

Answer 1

The sign of the entropy change for the given processes are: (a) negative due to a reduction in gaseous molecules, (b) negative due to solidification, (c) negative due to precipitation, and (d) positive due to dissociation into more gas particles.

Step-by-step explanation:

Predict the sign of the entropy change, ΔS, for each of the following processes:

1. Gaseous H2 reacts with liquid palmitoleic acid to form liquid palmitic acid: The entropy change is expected to be negative. This is because the number of gaseous molecules is being reduced as hydrogen gas is consumed to form a more ordered liquid structure, representing a decrease in the disorder of the system.
2. Liquid palmitic acid solidifies at 1 °C to solid palmitic acid: The entropy change is expected to be negative. The process of solidification results in a more ordered state and a decrease in the dispersal of the substance's particles.
3. Silver chloride precipitates after mixing aqueous silver ions and chloride ions: The entropy change is expected to be negative. When a precipitate forms, there is a reduction in the number of free ions in solution, hence a decrease in matter dispersal.
4. Gaseous H2 dissociates in an electric arc to form gaseous hydrogen atoms: The entropy change is expected to be positive. The dissociation of molecular hydrogen into individual atoms results in an increase in the number of gas particles and an increase in disorder.