Question

Predict how the entropy of the substance is affected in each of the processes. a) N₂(1,75 K) →→→ N₂(g, 100 K) b) CO₂(1,-57 °C) - CO,(g, 57 °C) c)CO₂(g, 57 °C) → CO₂ (s, -80 °C)

Answer 1

The entropy of a substance increases when it changes from a solid or liquid to a gas and when the temperature increases. Conversely, entropy decreases when a substance undergoes a phase change from gas to solid and when its temperature decreases.

Step-by-step explanation:

Entropy is a measure of the disorder or randomness in a system. When predicting the entropy change during processes, we consider phase changes, temperature changes, and changes in the number of moles of gases.

(a) For N2(l, 1.75 K) to N2(g, 100 K), we observe phase change from liquid to gas along with an increase in temperature. Both changes lead to an increase in entropy, as gas particles have more freedom of movement and kinetic energy than liquid particles.

(b) CO2(s, -57 °C) to CO2(g, 57 °C) involves a phase change from solid to gas and a temperature increase. This change also results in an increase in entropy, since the solid structure becomes dispersed in the gas phase, and thermal motion increases.

(c) CO2(g, 57 °C) to CO2(s, -80 °C) is the reverse; gas condenses to solid and temperature decreases, both leading to a decrease in entropy. Gas molecules are confined in a crystalline structure, reducing disorder.