Question

The least random state of a water system is (a) ice (b) liquid water (c) steam (d) equal randomness in all

Short answer

The least random state of a water system is (a) ice.

Step-by-step solution

Understanding the states of water

The three given options describe the three physical states of water: Ice (solid), liquid water (liquid) and steam (gas). In solid state, the particles are closely packed in a regular pattern resulting in very low randomness. In the liquid state, the particles have some freedom to move, resulting in moderate randomness. In gaseous state, the particles have total freedom and can occupy all the available space, resulting in high randomness.

Applying the concept of entropy

The randomness of a state is linked to its entropy. The higher the randomness, the higher the entropy. Since we are looking for the least random state, we are essentially looking for the state with the lowest entropy.

Choosing the right option

After understanding the concept and how it is related to the different states of matter, we can conclude that the correct answer is the state of water with the lowest entropy, which, as mentioned earlier, is the most ordered state, that is the solid state (ice).

Key concepts

Randomness in Physical States

When we talk about randomness in physical states, we are referring to how the particles in a substance are arranged and how freely they can move. Think of it like a messy room versus a tidy one. In a physical state, randomness is high if the particles are not organized in any particular order and can move around freely.
In contrast, when particles are arranged in a fixed pattern and have minimal movement, that state has low randomness.

• In solids like ice, particles are tightly packed in an organized manner, resulting in very low randomness.
• In liquids, particles have some freedom to move, leading to moderate randomness.
• In gases like steam, particles have total freedom to move, resulting in high randomness.

Understanding this concept helps in comparing different states of matter based on their internal particle arrangements.

Entropy and Order

Entropy is a concept often described as a measure of disorder or randomness in a system. When energy is spread out in a system or when particles are disordered, the system has high entropy.

• Solids have the lowest entropy because their particles are in an ordered structure.
• Liquids have higher entropy than solids because their particles can move around more freely, but less than gases.
• Gases have the highest entropy due to their particles being highly mobile and widely spaced.

The relationship between entropy and order is inversely proportional: as order increases, entropy decreases, and vice versa. This relationship is vital in understanding different thermodynamic processes.

States of Water

Water, a fundamental molecule for life, exists in three states: solid (ice), liquid (water), and gas (steam). Each of these states has distinct characteristics based on temperature and pressure.

• Ice is a solid where water molecules are structured in a fixed, rigid lattice, making it the least random and lowest entropy state.
• Liquid water particles have more energy than in ice, allowing them to move freely while still being relatively close together, resulting in moderate entropy.
• Steam particles are highly energetic and free to disperse widely, leading to high randomness and maximum entropy.

These states illustrate how water transitions between phases and demonstrate changes in particle arrangement and movement.

Entropy in Solids vs Liquids vs Gases

Entropy in solids, liquids, and gases varies significantly due to differences in particle arrangement and movement freedom. Solids have a very orderly structure with fixed particle positions, leading to the lowest entropy among the three states.
Liquids, on the other hand, have a disordered structure with particles that can move but still remain relatively close, giving them a moderate level of entropy. In gases, particles move freely and occupy all available space, leading to the highest level of entropy.

• Solid state: lowest entropy, high order.
• Liquid state: moderate entropy, medium order.
• Gas state: highest entropy, low order.

This understanding helps clarify why certain physical phenomena occur, such as the spontaneous mixing of gases or melting of ice, as systems tend to move towards higher entropy.