Lecture 4 - Thermal Physics PDF

2-Thermal Physics Dr.H.Elhendawi Fall 2024/2025 1 2.1 Kinetic particle model of matter States of matter Particle model 2.2 Thermal properties and temperature Thermal expansion of matter Specific heat capacity Latent heat 2.3 Transfer of thermal energy. Methods of...

2-Thermal Physics Dr.H.Elhendawi Fall 2024/2025 1 2.1 Kinetic particle model of matter States of matter Particle model 2.2 Thermal properties and temperature Thermal expansion of matter Specific heat capacity Latent heat 2.3 Transfer of thermal energy. Methods of heat transfer Consequences of thermal energy transfer Dr.H.Elhendawi Fall 2024/2025 2  1- Concepts 1- Thermal in physics It is the study of heat. Heat energy, or thermal energy, is the energy of a substance or system in terms of the motion or vibration of its molecules. 2- Heat (Q) 3- Temperature (T) 4- Internal Energy (U) Energy transfers A measure of the It is the total energy from hot to cold body average kinetic associated with the due to temperature energy of the particles microscopic components of difference. in the substance. the system (potential and Unit KJ, J or cal Unit k, oC ,oF, oR kinetic energy) Unit KJ, J Dr.H.Elhendawi 3 5- Heat Capacity It is the amount of heat requires to increase the temperature of the system. It is the amount of heat energy needed to raise the object’s temperature by one degree. Q = mc∆𝑇 It depends on both mass and its chemical structure. Is a measure of how well a substance store energy. Dr.H.Elhendawi 4  6- Specific Heat Capacity The amount of heat per unit mass required to raise the temperature by one. Symbol by c C=mc 7- Latent Heat (L) The amount of heat required to change the phase of the substance without change the its temperature. 𝑸 = 𝒎𝑳 Dr.H.Elhendawi 5  8- Macroscopic & Microscopic Properties Property Macroscopic Microscopic Scale of Macroscopic Observation macroscopic level with the naked eye. microscopic level using specialized tools or instruments. Components Describe the behavior of bulk matter Describe the behavior and and results from the arrangement and interactions of individual interactions of molecules, ions. particles (atoms, molecules, etc.). Examples Temperature, pressure, volume, density, Atomic mass, molecular bond color, and texture. lengths, bond energies, electron spin, and quantum states of individual particles. Units of Measurement Large units like kilogram, liter, and Small units like micrometer, gram/liter. milligram, and angstrom. Dr.H.Elhendawi 6 9- Extensive and Intensive Properties Extensive Intensive These properties are amount dependent. These properties are amount independent. Examples Mass, volume, energy, enthalpy, Examples Color, temperature, density, entropy, length and heat capacity. pressure, melting and boiling point, density, Surface tension and ductility. Dr.H.Elhendawi Fall 2024/2025 7  2.1 Kinetic particle model of matter State of Matter? Describe the physical forms matter can taken Solid , Liquid , Gas , Plasma Confirm macroscopic properties. Particle Theory of Matter? Explains matter ‘s microscopic properties Solid , Liquid , Gas , Plasma Confirm microscopic properties. Dr.H.Elhendawi Fall 2024/2025 8 Know the distinguishing properties of solids, liquids and gases ‫معرفة الخصائص المميزة للمواد الصلبة والسوائل والغازات‬. Know the terms for the changes in state between solids, liquids and gases..‫معرفة مصطلحات التغيرات في الحالة بين المواد الصلبة والسوائل والغازات‬ Dr.H.Elhendawi 9  Particle theory of matter? Solid Liquid Gas Plasma Melting Ionization Vaporization Freezing Condensation deionization The particles are The particles are The particles are Plasma is arranged in a regular close together but far apart and superheated matter. repeating. randomly arranged. randomly arranged. the electrons are The particles are The particles are free The particles are ripped away from vibrated around fixed to move around each free to move in any the atoms forming position. other. direction. an ionized gas. Add heat 4 Dr/ Habiba Elhendawi Question 1 Compare between solid, gas and liquid states in 1. Arrangement of particles. 2. Motion of particles. 3. Diagram. 1 Dr.H.Elhendawi 1  1 Dr.H.Elhendawi 2  Ideal Gas Properties All collisions between atoms or molecules are perfectly elastic. 2- The intermolecular attractive forces does not exist. 3- The molecules don't interact with each other. 4- All the internal energy is in form of kinetic energy and any change in the internal energy is accompanied by a change in temperature 1 Dr.H.Elhendawi 3  Ideal Gas Variables 1- Pressure (P) 2- Volume (V) 3- Temperature (T) 𝑃𝑉 = 𝑛𝑅𝑇 n: number of moles R: the universal gas constant = 8.3145 J/mol.K 1 Dr.H.Elhendawi 4 The relationship between the motion of particles and temperature The higher the temperature the more kinetic energy the gas Describe qualitatively the pressure of a gas in terms of the motion of its molecules. The higher pressure is exerted on the gas, the gas molecules gain kinetic energy, causing them to move faster and more erratically 1 Dr.H.Elhendawi 5 Explain qualitatively, in terms of particles, the relationship between: (a) pressure and temperature at constant volume (b) volume and temperature pressure and volume At constant temperature Volume and pressure are inversely proportional. At constant pressure Temperature and volume are directly proportional. At constant volume Temperature and pressure are directly proportional. 1 10 Dr.H.Elhendawi 6 https://phet.colorado.edu/sims/html/gases-intro/latest/gases-intro_all.html 1 10 Dr.H.Elhendawi 7 https://phet.colorado.edu/sims/html/gases-intro/latest/gases-intro_all.html 1 10 Dr.H.Elhendawi 8  Pressure Law 𝑃1 𝑃2 = 𝑇1 𝑇2 Ex Helium gas enters a nuclear reactor at 9.20 MPa AT temperature 510 𝑜 𝐶.It leaves the reactor at a temperature of 977 𝑜 𝐶. Calculate the pressure of the Helium gas leaves the reactor. Solution 𝑇1 = 510 + 273 = 783 𝐾 𝑇2 = 977 + 273 = 1250 𝐾 𝑃1 𝑃2 = 𝑇1 𝑇2 𝑃2 𝑇1 9.20𝑥1250 𝑃2 = = = 14.70 𝑀𝑃𝑎 𝑇2 783 1 12 Dr.H.Elhendawi 9  Question 2 Which graph shows the pressure-temperature relationship for a gas at a fixed volume? 2 10 Dr.H.Elhendawi 0  Question (3) Classify each of the following as an intensive property [I] or an extensive property [E]. 1) Mass ___________ 4) Temperature ___________ 2) Density ___________ 5) Volume ___________ 3) Melting point ___________ 6) Heat ___________ Question (4) Three balloons are each filled with a different gas: hydrogen (0.0899 g/L), carbon dioxide (1.977 g/L), and helium (0.1785 g/L). The balloons are released into the air. Which balloon will float the highest in the air (air has a density of 1.29 g/L)? __________________________________ 2 Dr.H.Elhendawi 1 22