Galala University Lecture Notes on Liquid and Solid States - 2024-2025 PDF

 Course Basic Information Level / Semestre: level 1, Fall Semestre, 2024-2025 Course Name: Engineering Chemistry Course Code: CHE142 Course Instructors: Dr. Ahmed Ibrahim Instructors Emails: [email protected] Field/Department responsible...

 Course Basic Information Level / Semestre: level 1, Fall Semestre, 2024-2025 Course Name: Engineering Chemistry Course Code: CHE142 Course Instructors: Dr. Ahmed Ibrahim Instructors Emails: [email protected] Field/Department responsible for the course: Basic Sciences / Chemistry Program (s) Title: Engineering program Course Hours: 3 Credit hours Contact Hours= 2 hours lecture (2 Cr. Hr) + 2 hours laboratory (1 Cr. Hr) 2  Important Instructions  Instructor Office hours: Wednesday 10:40 am – 12:20 pm Sunday and Monday during the break time Basic Sciences Building, Third floor, Office No: 3-35.  Instructor Contact Methods: Office Academic email: [email protected] Private message through Canvas 3  Important Instructions  No body will attend the exam if the attendance percent is lower than 75 % (Very Important).  No lab report’s marking without physical attendance.  It’s NOT ALLOWED at all to submit any assignment (or quiz) after the deadline. Even it happens with accepted excuse, you will lose 50 % of the mark.  It’s NOT ALLOWED at all to come to the labs LATE.  The course project details will be announced soon.  The first course assignment/quiz will be announced soon. 4  Select Properties of Liquids Viscosity The resistance of a liquid to flow. The greater a liquid’s viscosity, the more slowly it flows. The higher the molecular weight, the higher the viscosity.  Select Properties of Liquids Surface tension The surface of water behaves almost as if it had an elastic skin, as evidenced by the ability of certain insects to “walk” on water. This behavior is due to an imbalance of intermolecular forces at the surface of the liquid. Molecules in the interior are attracted equally in all directions, but those at the surface experience a net inward force. This net force tends to pull surface molecules toward the interior, thereby reducing the surface area and making the molecules at the surface pack closely together.  Introduction Solids and/or Crystals are everywhere! https://thechemistrynotes.com/crystalline-vs-amorphous-solids/ https://www.expii.com/t/crystal-lattice-structure-formation-7999 Solids and/or Crystals Crystals are solid but solids are not necessarily crystalline. Crystals have symmetry and long range order. Spheres and small shapes can be packed to produces Dense, Non dense, regular shapes. ordered packing random packing  Introduction Solid Classification Solid Materials Crystalline Amorphous (non-crystalline) Single Crystal Polycrystalline Not Periodic Atoms have no periodic packing Periodic across the whole volume Occurs for complex structures and rapid cooling Atoms pack in periodic, 3D arrays Periodic across each grain  Introduction Energy and Packing Energy Non dense, random packing typical neighbor bond length r typical neighbor bond energy Dense, ordered packing Energy typical neighbor bond length typical neighbor r bond energy Dense, ordered packed structures tend to have lower energies  Important Definitions Crystal Structure Crystal structure of the material is the manner in which atoms, ions, or molecules are spatially arranged. Crystal Lattice and unit cell Crystal Lattice is an infinite three-dimensional array of points in space. Each point has identical surroundings to all others. Arrays are arranged exactly in a periodic manner. Unit cell Crystal structures is subdivided into small repeat entities called unit cells. A unit cell is chosen to represent the symmetry of the crystal structure. Thus, the unit cell is the basic structural unit or building block of Crystal lattice structure the crystal structure and defines the crystal structure by virtue of its geometry (symmetry) and the atom positions within.  Important Definitions Lattice Parameters and Interaxial Angles The lattice parameters are the axial lengths or dimensions of the unit cell and are denoted by convention as a, b, and c. The angles between the axial lengths, known as the interaxial angles, are denoted by the Greek letters α, β and γ. To fully define a unit cell, the lattice parameters or ratios between the axial lengths, interaxial angles, and atomic coordinates must be specified. The unit cell is a box with: 3 axial lengths: a, b, c 3 interaxial angles: α, β and γ  Crystal Systems The Seven Crystal Systems https://www.sarthaks.com/883507/draw-the-seven-types-of-primitive-crystal-systems  Crystal Systems (cont.) Types of unit cells Important video https://www.youtube.com/watch?v=Rm-i1c7zr6Q  Simple Cubic Structure (SC) Rare due to low packing density. Close-packed directions are cube edges. Coordination (nearest neighbors) = 6  Face Centered Cubic Structure (FCC) Atoms touch each other along face diagonals. All atoms are identical; the face-centered atoms are shaded differently only for ease of viewing. Example: Al, Cu, Au, Pb, Ni, Pt, Ag Coordination (nearest neighbors) = 12 4 atoms/unit cell: (6 face x ½) + (8 corners x 1/8)  Body Centered Cubic Structure (BCC) Atoms touch each other along cube diagonals. All atoms are identical; the center atom is shaded differently only for ease of viewing. Examples: Cr, W, Tantalum, Molybdenum Coordination (nearest neighbors) = 8 2 atoms/unit cell: (1 center) + (8 corners x 1/8)  DETERMINATION OF CRYSTAL STRUCTURES X-RAY DIFFRACTION (XRD) X-ray is a type of electromagnetic radiation X-ray diffraction investigations help in understanding the atomic and molecular arrangements in solids  What is electromagnetic radiation? Electromagnetic radiation is a form of energy that travels through space in waves at a speed of 3×108 m/s (the speed of light) and exhibits wave properties. The three characteristics of waves are wavelength and frequency and amplitude (half the distance from the crest of a wave to its trough). All these waves travel at the same speed through a vacuum but they differ in wavelength and frequency. Wavelength (λ) is the distance between identical points on successive waves. Amplitude (A) is the vertical distance from the midline of a wave to the peak or trough. Frequency (ν) is the number of waves that pass through a particular point in 1 second (Hz = 1 cycle/s). All electromagnetic radiation λ×ν=c 20  THE ELECTROMAGNETIC SPECTRUM Type of radiation 21  DETERMINATION OF CRYSTAL STRUCTURES X-RAY DIFFRACTION (XRD) A diffractometer is a measuring instrument for analyzing the structure of a material from the scattering pattern produced when a beam of radiation or particles (such as X-rays or neutrons) interacts with it.  DETERMINATION OF CRYSTAL STRUCTURES X-RAY DIFFRACTION (XRD) X-rays to determine crystal structure reflections must be in phase for The incoming X-rays beam (coming from a detectable signal extra λ upper left) diffract from crystal planes. distance travelled θ θ by wave “2” spacing d between In that case, part of the incoming beam is planes deflected by an angle 2θ, producing a reflection spot in the diffraction pattern. Measurement of critical angle, θc, allows computation of planar spacing, d. Bragg’s law n λ = 2d Sin θc n is the order of reflection  DETERMINATION OF CRYSTAL STRUCTURES X-RAY DIFFRACTION (XRD) X-Ray Diffraction Pattern z z z c c c y(110) y y a b a b a b Intensity (relative) x x x (211) (200) Diffraction angle 2θ Diffraction pattern for polycrystalline α-iron (BCC) Adapted from Fig. 3.22, Callister 8e.  Alloys Solids can dissolve in solids, giving alloys, such as copper in silver. Why? Increase the hardness of the metal Lower the melting point Increase corrosion resistance  Learning Resources Theodore Brown, et al. “Chemistry: The Central Science (MasteringChemistry)”. 14th Edition. Pearson; 2017. ISBN-10 : 9780134414232, ISBN-13 : 978-0134414232 Raymond Chang and Kenneth Goldsby: “General Chemistry: The Essential Concepts”. 7th Edition, McGraw Hill Higher Education, New York, 2014. ISBN10: 0073402753, ISBN13: 9780073402758 Rich Bauer and James Birk and Pamela Marks. “Introduction to Chemistry”. 5th edition. McGraw Hill Higher Education, New York, 2019. ISBN10: 1259911144 P.C. Jain. “Engineering chemistry”. 16th edition, 2015, ISBN-13: 978-9352160006 Shikha Agarwal. “Engineering Chemistry: Fundamentals and Applications”. 2nd Edition, 2019, ISBN: 9781108724449