Question

Kinetic energy of molecule is highest in (1) Gases (2) Liquids (3) Solids (4) Solutions

Short answer

Gases

Step-by-step solution

Understand Kinetic Energy

Kinetic energy is the energy an object has due to its motion. For molecules, this means how fast they are moving.

Compare States of Matter

Consider the different states of matter: solids, liquids, and gases. In solids, molecules are tightly packed and have limited movement. In liquids, molecules are less tightly packed and move more freely. In gases, molecules are far apart and move very quickly.

Analyze Each Option

Evaluate each option: (1) In gases, molecules have the highest freedom of movement. (2) In liquids, molecules move but not as freely as in gases. (3) In solids, molecules are restricted to very limited movement. (4) Solutions consist of a solute in a solvent, and the state of matter of the solvent will determine the movement.

Determine the Highest Kinetic Energy

Since molecules in gases have the most freedom to move, they have the highest kinetic energy compared to those in liquids, solids, and solutions.

Key concepts

States of Matter

Matter exists in three primary states: solids, liquids, and gases. In solids, particles are tightly packed in a fixed, rigid structure. They can only vibrate slightly around fixed positions. This means their kinetic energy is quite low. In liquids, particles are less tightly packed and can move around each other, giving them moderate kinetic energy. Gases, on the other hand, have particles that are very far apart and move independently at high speeds. This results in high kinetic energy. Understanding these differences helps us comprehend how substances behave in different conditions and affects their physical properties.

• Solids: Fixed shape and volume, low kinetic energy.
• Liquids: Indefinite shape, definite volume, moderate kinetic energy.
• Gases: Indefinite shape and volume, high kinetic energy.

Molecular Motion

Molecular motion refers to the movement of particles within a substance. The speed and nature of this movement differ based on the state of matter. In gases, molecules move rapidly and collide frequently, demonstrating high kinetic energy. Liquid molecules move more freely than in solids but are still somewhat constrained by intermolecular forces, resulting in moderate kinetic energy. In solids, molecular motion is limited to vibrations around fixed positions, leading to low kinetic energy. The degree of this motion is influenced by temperature: as temperature increases, molecular motion and kinetic energy also increase.

• Gases: Frequent, fast motion, high kinetic energy.
• Liquids: Moderate, constrained motion, moderate kinetic energy.
• Solids: Slow vibrations, low kinetic energy.

Gases

Gases are characterized by having neither a fixed shape nor a fixed volume. Their molecules are far apart and move very quickly. This high speed allows gas molecules to fill any container they are placed in, spreading out to evenly distribute themselves. As a result, gases are highly compressible and respond significantly to changes in temperature and pressure. According to the kinetic molecular theory, the behavior of gases can be explained by the high kinetic energy of their molecules. The gases' molecules are in constant, random motion, colliding with the walls of their container and each other. This motion and collision account for gas pressure and the fact that gases don't have a fixed shape or volume.

• Indefinite shape and volume.
• High compressibility.
• High kinetic energy due to rapid, random motion.

Kinetic Theory

The kinetic theory of matter explains the behavior of particles in different states of matter. It posits that all matter is made up of particles (atoms or molecules) that are in constant motion. The energy associated with this motion is known as kinetic energy. In gases, kinetic theory helps explain why gas particles move quickly and spread out to fill any container. It states that the kinetic energy of gas particles is directly proportional to the temperature. Higher temperatures result in more kinetic energy and faster-moving particles. The theory also explains how gas pressure results from collisions of gas particles with the container walls.

• All particles are in constant motion.
• Kinetic energy increases with temperature.
• Gas pressure is due to particle collisions with container walls.

Understanding kinetic theory can help explain various phenomena, such as the expansion of gases when heated and the diffusion of substances in air. It bridges the gap between macroscopic observations (like temperature and pressure) and microscopic behaviors (like molecular motion).