Chapter 10 - Chapter 10 Section 1 The Kinetic-Molecular Theory of Matter \u25cf Kinetic molecular \u25cb The kinetic-molecular theory based on the idea that

Chapter 10 - Chapter 10 Section 1 The Kinetic-Molecular...

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Chapter 10 Section 1: The Kinetic-Molecular Theory of Matter Kinetic molecular The kinetic-molecular theory : based on the idea that particle of matter are always in motion The Kinetic Molecular Theory of Gases Ideal gas : a hypothetical gas that perfectly fits all the assumptions of the kinetic-molecular theory The kinetic molecular theory is based on the following five assumptions 1. Gases consist of large numbers of tiny particles that are far apart relative to their size Most of the volume occupied by a gas is empty space (Multiple Choice Question) 2. Collisions between gas particles and between particles and container walls are elastic collisions An elastic collision is one in which there is no net loss of total kinetic energy 3. Gas particles are in continuous, rapid, random motion. They therefore possess kinetic energy, which is energy of motion 4. There are no forces of attraction between gas particles 5. The temperature of a gas depends on the average kinetic energy of the particles of the gas The kinetic energy of any moving object is given by the following equation: KE = 1/2mv 2 All gases at the same temp have the same average kinetic energy At the same temp, lighter gas particles have higher average speeds than do heavier gas particles Hydrogen molecules will have a higher speed than oxygen molecules The Kinetic-Molecular Theory and the Nature of Gases The kinetic-molecular theory applies only to ideal gases Many gases behave nearly ideally if pressure is no very high
Expansion Gases do no have a definite shape or a definite volume They completely fill any container in which they are enclosed Gas particles move rapidly in all directions (assumption 3) without significant attraction between them (assumption 4) Fluidity Because the attractive forces between gas particles are insignificant (assumption 4), gas particles glide easily past one another Because liquids and gases flow, they are both referred to as fluids . Low density The density of a gaseous substance at atmospheric pressure is about 1/1000 the density of the same substance in the liquid or solid state The reason is that the particles are so much farther apart in the gaseous state (assumption 1). Compressibility During compression, the gas particles, which are initially very far apart (assumption 1), are crowded closer together Diffusion and effusion Gases spread out and mix with one another, even without being stirred The random and continuous motion of the gas molecules (assumption 3) carries them throughout the available space Such spontaneous mixing of the particles of two substances cause by their random motion is called diffusion.

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