Polymer Chemistry Quiz
45 Questions
1 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What characterizes linear polymers?

  • They contain numerous side branches.
  • They have a high density and rigidity.
  • They are resistant to hydrogen bonding.
  • They are composed of end-to-end joined repeat units. (correct)

    • How does branching affect the density of polymers?

  • It increases the packing efficiency.
  • It makes the polymer more rigid.
  • It reduces the density of the polymer. (correct)
  • It has no effect on density.

    • What is a characteristic of cross-linked polymers?

  • They exhibit no elasticity.
  • They are composed of covalently bonded chains at various positions. (correct)
  • They consist only of linear chains.
  • They form weak van der Waals forces between chains.

    • What defines a network polymer?

    <p>It is formed by multifunctional monomers creating a three-dimensional network.</p> Signup and view all the answers

    Which of the following is a common feature of high-density polyethylene (HDPE)?

    <p>It is a linear polymer with high molecular density.</p> Signup and view all the answers

    What is the common oxidation state of alkali metals?

    <p>+1</p> Signup and view all the answers

    Which element is the lightest known metal among alkali metals?

    <p>Lithium</p> Signup and view all the answers

    How do alkaline earth metals compare to alkali metals in terms of reactivity?

    <p>Less reactive</p> Signup and view all the answers

    What is the principal ore of aluminum?

    <p>Bauxite</p> Signup and view all the answers

    What unique property does aluminum have in the periodic table?

    <p>Does not occur in nature in elemental form</p> Signup and view all the answers

    What is the oxidation state of alkaline earth metals?

    <p>+2</p> Signup and view all the answers

    What is used as a solvent in the Hall process for aluminum production?

    <p>Cryolite</p> Signup and view all the answers

    What is the structure type of alkali metals?

    <p>Body-Centered Cubic (BCC)</p> Signup and view all the answers

    Why is iron not typically used alone in construction?

    <p>It is usually too soft.</p> Signup and view all the answers

    What methods are commonly used to protect iron and steel from rust?

    <p>Applying a layer of paint.</p> Signup and view all the answers

    What is the root meaning of the word 'polymer'?

    <p>Many units.</p> Signup and view all the answers

    Which of the following is a characteristic of natural polymers?

    <p>They can be extracted from nature.</p> Signup and view all the answers

    When were synthetic polymers first developed?

    <p>In the early 20th century.</p> Signup and view all the answers

    Which of the following is NOT an example of a synthetic polymer?

    <p>Natural rubber.</p> Signup and view all the answers

    What property is typically associated with polymers?

    <p>High molar mass and many repeating units.</p> Signup and view all the answers

    What differentiates thermoplastic polymers from thermosetting polymers?

    <p>Thermoplastics remain flexible upon heating.</p> Signup and view all the answers

    What is the basic structural unit of a crystal structure called?

    <p>Unit Cell</p> Signup and view all the answers

    Which type of crystal structure has atoms positioned only at the corners of a cube?

    <p>Simple Cubic</p> Signup and view all the answers

    What is the coordination number for Face-Centered Cubic (FCC) crystal structures?

    <p>12</p> Signup and view all the answers

    Which element is known to possess a simple cubic structure?

    <p>Polonium</p> Signup and view all the answers

    In a Body-Centered Cubic (BCC) structure, where are the atoms located?

    <p>At corners and the center</p> Signup and view all the answers

    What aspect is used for computing the density of a solid from its unit cell?

    <p>Volume of the unit cell</p> Signup and view all the answers

    What happens to thermoplastics upon heating?

    <p>They soften and then can harden again.</p> Signup and view all the answers

    Which is NOT a type of crystal structure covered in the content?

    <p>Hexagonal Close-Packed</p> Signup and view all the answers

    What is a characteristic of amorphous solids?

    <p>Lack of long-range order</p> Signup and view all the answers

    Which polymer is characterized by being transparent, strong, and impervious to acids and atmospheric gases?

    <p>Polyethylene terephthalate</p> Signup and view all the answers

    Which of the following is a characteristic of thermosetting polymers?

    <p>They become permanent during formation.</p> Signup and view all the answers

    Which type of polymer arrangement is described as having different repeat units dispersed randomly?

    <p>Random copolymers</p> Signup and view all the answers

    What is a primary use for polyvinyl chloride (PVC) when it is rigid?

    <p>Building siding</p> Signup and view all the answers

    What distinguishes thermoplastics from thermosets in terms of thermal response?

    <p>Thermoplastics do not contain covalent crosslinks.</p> Signup and view all the answers

    Which characteristic is true for polypropylene (PP)?

    <p>Very tough and has a high melting point</p> Signup and view all the answers

    What is the primary feature of block copolymers?

    <p>They have sections of identical repeat units clustered.</p> Signup and view all the answers

    What is the main property of polyethylene (PE) that differentiates it from low-density polyethylene (LDPE)?

    <p>More rigid and tougher than LDPE</p> Signup and view all the answers

    What best describes polymer crystallinity?

    <p>The packing of molecular chains in an ordered structure.</p> Signup and view all the answers

    In which products is polystyrene (PS) typically used in its crystal form?

    <p>Food wrap and CD cases</p> Signup and view all the answers

    What can excessive heating do to thermoset polymers?

    <p>Cause polymer degradation.</p> Signup and view all the answers

    Which polymer is described as soft and flexible and unreactive to acids and bases?

    <p>Polyethylene</p> Signup and view all the answers

    Which of the following is NOT an example of thermoplastic polymers?

    <p>Epoxies</p> Signup and view all the answers

    What is a common application for expandable polystyrene?

    <p>Insulated containers</p> Signup and view all the answers

    What makes polyethylene terephthalate (PETE) the costliest among common polymers?

    <p>Its manufacturing process</p> Signup and view all the answers

    Study Notes

    Chemistry of Engineering Materials: Metals

    • Metals are elements, compounds, or alloys that conduct electricity and heat well.
    • Metals are typically solids at room temperature, except for mercury.
    • Metals are characterized by bright luster, hardness, the ability to resonate sound, and are excellent conductors of heat & electricity.
    • Metals are typically solids at room temperature, except for mercury and gallium (sometimes liquid at higher temperatures).
    • Metals are characterized by the ability to be hammered into sheets (malleability).
    • Metals also have the ability to be drawn into wires (ductility).

    Learning Objectives

    • Introduce metals
    • Describe the occurrence and abundance of metals in the Earth's crust
    • Explain the metallurgical processes
    • Explain the Band Theory of Electrical Conductivity
    • Discuss the periodic trends of metals and their reactivity

    Metal

    • Metals are elements, compounds, or alloys that conduct electricity and heat.
    • Their crystal structures determine their specific properties.

    Metal (cont.)

    • With the exception of hydrogen, elements that form positive ions during chemical reactions are called metals.
    • Metals are solids under normal conditions, except for mercury.

    Metals on Periodic Table

    • A periodic table is presented identifying metals in various groups.

    Physical Properties of Metal

    • State: Most metals are solids at room temperature, except for mercury. Gallium is liquid at higher temperatures.
    • Luster: Metals reflect light from their surface and can be polished.
    • Malleability: Metals can be hammered into thin sheets.
    • Ductility: Metals can be drawn into wires.
    • Hardness: All metals are hard, except sodium and potassium which are soft and can be cut with a knife.
    • Valency: Metals typically have 1 to 3 electrons in their outermost shell..
    • Density: Metals have high density, with Iridium and Osmium having the highest. Lithium has the lowest.
    • Melting and Boiling Points: Metals generally have high melting and boiling points, except mercury and sodium/potassium.

    Chemical Properties of Metal

    • Electropositive Character: Metals tend to have low ionization energies, losing electrons when undergoing chemical reactions. They usually do not accept electrons.

      • Alkali metals: Always +1 (lose the s-subshell electron).
      • Alkaline earth metals: Always +2 (lose both s-subshell electrons).
      • Transition metals: Ion charges vary (lose s and some d-subshell electrons).

    • Chemical reactions are shown, illustrating oxidation states of metals (Na, Mg, Al).

    Occurrence of Metal

    • Most metals come from minerals.
    • A mineral is a naturally occurring substance with a range of chemical compositions.
    • An ore is a mineral deposit concentrated enough for economical metal recovery.
    • Metals exist in various forms—within Earth's surface, as seawater ions, and in the ocean floor.
    • Important metals are found in several different forms, and in varying concentrations.
    • Representative minerals are given.
      • Examples of minerals—clay; bauxite
    • Some metals are most readily found in seawater.

    Metallurgy

    • Metallurgy involves separating metals from their ores.
    • This includes preparation, production, and purification.
    • Preparation: Separation of desired metal from gangue/waste material
      • Methods include flotation, magnetic separation and amalgamation.

    Production of Metals

    • Processes for metal purification
      • Chemical reduction
      • Electrolytic reduction
      • Pyrometallurgy

    Production of Metal (cont.)

    • Specific examples of metal production, including iron.

    Steelmaking

    • Steel is an alloy of iron with small amounts of carbon and various other elements.
    • Steelmaking involves oxidation processes to remove impurities.
    • The basic oxygen process is a widely used simplification.
    • Flux removes oxidized impurities.
    • The cooling rate of the molten steel, called tempering, adjusts the carbon content and final product properties.
    • A table with different steel types and their compositions.

    Purification of Metals

    • Metals require further treatment to remove impurities after reduction.
    • Distillation, electrolysis, and zone refining are common purification methods.

    Band Theory of Electrical Conductivity

    • In solid-state physics, band theory describes the possible allowed energy ranges (bands) for electrons within solids.
    • The theory postulates the existence of energy bands for electrons (allowed & forbidden bands).
    • Band theory explains how electrons move in solids which can be used to understand conductivity.

    Band Theory (cont.)

    • Overlapping molecular orbitals produce bands in solids—valence band (low energy) & conduction band (higher energy)
    • Band gap separating valence & conduction band; negligible gap = good conductor; large gap = insulator
    • Metals (no band gap) are good electrical conductors.
    • Semiconductors have a small band gap which causes their conductivity to be controlled by extrinsic factors.

    Semiconductors

    • Semiconductors can normally conduct electricity at high temperatures or when combined with other elements.
    • Group 4A elements are semiconductors (esp silicon & germanium).

    Semiconductors (cont.)

    • Doping semiconductors can raise their conductivities.
    • There are two doped categories—n-type (negative charge carriers) & p-type (positive charge carriers).

    Alkali Metals

    • Alkali metals are elements in group 1.
    • They are silvery, cut easily with a knife, and have low density.
    • Hydrogen doesn't always exhibit alkali metal properties.
    • The word "alkali" comes from Arabic; meaning "from ashes".
    • Alkali metals react with water readily, forming alkaline solutions.

    Alkaline Earth Metals

    • Alkaline earth metals are Group 2 elements.
    • They are less reactive than alkali metals.
    • They have a higher melting point than alkali metals, and are harder.
    • The chemistry of radium is less well-studied due to its radioactivity.
    • Emerald is a prominent mineral that contains beryllium.

    Aluminum

    • Aluminum is the most abundant metal in the Earth's crust.
    • Bauxite (Al2O3 • H₂O) is its primary ore.
    • Other related minerals include orthoclase, beryl, cryolite, and corundum.

    Transition Metals

    • Transition metals occupy groups 3-12, with variable oxidation states.
    • They generally have incompletely filled d subshells that can be responsible for the colorful complexes & compounds they form.
    • Transition metals often serve as catalysts in chemical reactions—without being consumed in the process.

    Properties of Transition Metals

    • Physical properties of transition metals are similar:

      • good conductors of heat and electricity.
      • can be hammered or bent into shape easily.
      • high melting points (mercury is an exception).
      • usually hard and tough
      • high densities

    • Chemical properties of transition metals are more variable.

      • less reactive than alkali metals
      • form colored ions in compounds with different charges.
      • some are very unreactive (silver & gold)

    Uses of Transition Metals

    • Transition metals have many uses thanks to their properties:
      • Jewelry and electrical connectors
      • Electrical wires and printed circuits
      • Water pipes
      • Building materials (bridges, buildings, ships, cars)
      • Catalysts (chemical industry)
      • Coatings to prevent corrosion (e.g. chrome on car parts)

    Polymer Chemistry

    • Polymers are complex molecular compounds.
    • Polymers are composed of numerous repeating units.
    • Common sources of polymers include crude oil.
    • Natural polymers come from living organisms.
    • Synthetic polymers are created through lab reactions

    Polymer Structure: Types

    • Linear polymers: Repeat units link end-to-end; flexible; extensive van der Waals interactions possible
    • Branched polymers: Branches occur from the main chains; lower density; less efficient packing
    • Cross-linked polymers: linear chains cross-linked covalently; more rigid, less flexible
    • Network polymers: chains highly cross-linked in a 3D network; more rigid and durable.

    Polymer Chemistry: Properties

    • Molecular weight: The weight of the polymer affects its properties. Higher molecular weights typically mean higher melting/softening temperature.
    • Degree of Polymerization: The average number of repeat units in the chain, related to the number average molecular weight by a specific equation.

    Copolymers

    • Copolymers are polymers containing two types of repeat units.
    • Copolymer types:
      • Alternating: alternating arrangement of different repeat units.
      • Random/Statical: randomly arranged repeat units.
      • Block: repeating blocks of the same repeat units.
      • Graft: branches containing repeating units attached to a homopolymer chain.

    Polymer Crystallinity

    • Crystalline polymers have an ordered atomic arrangement.
    • Polymer crystallinity is the packing of molecular chains to form an ordered atomic array that can be determined via unit cells.

    Thermoplastic and Thermosetting Polymers

    • Thermoplastics: soften and liquefy upon heating, can be repeatedly melted & reshaped; characterized by a linear structure or branches that do not firmly bond together.
    • Thermosets: form a rigid network that is not altered upon heating. They have extensive cross-links that make them durable, but can't be melted or reshaped.

    Basic Concepts of Crystal Structures

    • Crystal Structures: Atoms and ions form an ordered and repeating set of units to form crystalline solids.
    • Unit Cells: The smallest repeating units in crystals. Various unit cell types exist; including simple cubic, body centered cubic, face centered cubic & hexagonal close packed cells.
    • Density Computations: Density can be calculated by knowing the unit cell's number of associated atoms, its atomic weight, its volume and Avogadro's number.
    • Types of Crystals: four basic categories - ionic, metallic, covalent & molecular.
    • Amorphous Solids: Solids without a crystal lattice structures, like glass.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Chemistry of Engineering Materials: Metals PDF

    Description

    Dive into the world of polymers with this quiz! Explore key characteristics of linear, branched, cross-linked, and network polymers, along with specific features of high-density polyethylene (HDPE). Test your knowledge on how these structures affect their properties.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser