2. 27.1 Describe the kinetic particle model for solids liquid and gases, and relate the difference in the structure and densities of solids, liquids and gases to the spacing, ordering and motion of particles subliming Boiling, vaporizing evaporating Liquefying , melting Freezing, solidtying Condensing, liquefying SOLID GAS LIQUID Molecules held in fixed Pattern but vibrating Molecules packed close Together in a random Fashion. Free to move Molecules widely Separated. Move at great speed
3. 27.2 Use the kinetic particle model to explain fluid pressure, freezing, melting, boiling, evaporation, crystallization and the brownian motion. Freezing Is a phase change in which a liquid turns into a solid when its temperature is lowered below its freezing point. Melting is a physical process that results in the phase change of a substance from a solid to a liquid Boiling is the rapid vaporization of a liquid, which occurs when a liquid is heated to a temperature such that its vapor pressure is above that of the surroundings
4. Evaporation is the process whereby atoms or molecules in a liquid state (or solid state if the substance sublimes) gain sufficient energy to enter the gaseous state. Crystallization is the slow precipitation of crystals from a solution of a substance. Crystallization can also refer to the solid-liquid separation and purification technique in which mass transfer occurs from the liquid solution to a pure solid crystalline phase. Brownian motion Is a random movement of microscopic particles suspended in liquids or gases resulting from the impact of molecules of the surrounding medium
5. 27.3 use the kinetic particle model to explain the thermal expansion of solids and liquids. List some of the problems this phenomenon can cause and how we solve them, and also list ways in which we make use of this phenomenon. Thermal Expansion general increase in the volume of a material as its temperature is increased. It is usually expressed as a fractional change in length or volume per unit temperature change; a linear expansion coefficient is usually employed in describing the expansion of a solid, while a volume expansion coefficient is more useful for a liquid or a gas. If a crystalline solid is isometric (has the same structural configuration throughout), the expansion will be uniform in all dimensions of the crystal. If it is not isometric, there may be different expansion coefficients for different crystallographic directions, and the crystal will change shape as the temperature changes.
6. 27.4 Use the concept of expansivity to solve numerical problems related to thermal expansion. The change in length L-L0 Length Before heating ΔL=α.L0.ΔT Linear coefficient The expansion after heating
7. 27.5 Explain how the anomalous expansion of water results in ice forming on the surface of water and not at the bottom, and understand the importance of this to the survival of living things. The Volume of water decries as the temperature increase from 0°C to 4°C . The volume again increase as the temperature is increase further from 4°C This odd behavior is shown below , the density of water is thus maximum at 4°C
8. 27.7 Understand and use the term pressure in the contexts of pressure exerted by a solid object and fluid pressure, and derive and use the relationship P=ρgh. Use a manometer to study how pressure increase with depth in water and how such fluid pressure is directionless. - Unit of temperature : degrees Celsius (°C), and Kelvin (K). - Unit of density: Kg/m³ - Unit of pressure: Pascal N/m² Volume ÷- Density = mass ρ= Kg/m³ Area ÷- Pressure= Force ρ= N/m²
9. 27.8 Explain, in terms of the particle model, the hydraulic transmission of a force and know and explain quantitatively some common applications.
10. 27.9 understand why some objects float on water but others do not, and relate up thrust on a floating body to the weight of the fluid displaced. Principle of Archimedes : It states that when a body is totally or partially immersed in a fluid it experiences an upthrust equal to the weight of the fluid displaced
