8.-Diffusion-and-the-Kinetic-Model-of-Matter Flashcards
What is diffusion?
The movement of particles from an area of higher concentration to an area of lower concentration.
Example: The smell of perfume spreading in a room.
What is kinetic theory?
A theory that explains the physical properties of matter in terms of the motion of its particles.
Key Idea: Particles are always in motion, and this motion increases with temperature.
What is a concentration gradient?
A difference in the concentration of a substance across a space.
Example: Higher concentration of sugar in one part of a cup of tea than another.
What is a semi-permeable membrane?
A membrane that allows small molecules such as water, carbon dioxide, and oxygen to pass through it, but does not allow large molecules to pass through.
What factors affect the rate of diffusion?
- Steepness of concentration gradient.
- Temperature – higher temperature increases molecular energy and speed.
- Size of molecules – smaller molecules diffuse quicker.
- Shape of molecules – streamlined shapes diffuse quicker.
- Distance – shorter distances allow quicker diffusion.
What is Brownian motion?
The random, jiggling movement of tiny particles suspended in a fluid due to constant bombardment by fast-moving atoms or molecules.
What is the kinetic model of matter?
A model that describes the arrangement of particles in solids, liquids, and gases:
- Solids: particles touching and in fixed positions.
- Liquids: particles close together, rolling over each other and arranged randomly.
- Gases: particles are far apart and arranged randomly.
What is dynamic equilibrium?
A state where the rate of diffusion is balanced, and there is no net movement of particles in one direction.
How does surface area affect diffusion?
The greater the surface area of a membrane, the faster the rate of diffusion of molecules through it. This is important for processes such as gas exchange in body cells.
