Adhesives and Adhesives Types

Chapter 4: Chemical Bonding and Catalysis

• Chemical bonding involves the loss and gain of electrons to form bonds.
• Types of bonds:
  • Covalent bond: formed by sharing of electrons between atoms.
  • Electrovalent bond: formed by complete transfer of electrons between atoms.
  • Coordinate bond: formed by donation of electrons from one atom to another.
• Catalysis: process of increasing the rate of a chemical reaction without being consumed by the reaction.
• Types of catalysis:
  • Homogeneous catalysis: catalyst is in the same phase as the reactants.
  • Heterogeneous catalysis: catalyst is in a different phase from the reactants.
  • Enzymatic catalysis: biological molecules that speed up chemical reactions.

Chapter 5: Metal Corrosion, its Prevention, and Electrochemistry

• Corrosion: destruction of metal due to chemical reaction with the environment.
• Factors affecting corrosion:
  • Presence of moisture and oxygen.
  • pH of the environment.
  • Presence of impurities.
• Prevention of corrosion:
  • Cathodic protection: attaching a more reactive metal to an iron object to act as an anode.
  • Sacrificial protection: using a more active metal to corrode instead of the iron object.
  • Galvanizing: coating iron with a layer of zinc to prevent corrosion.
• Electrochemical series: a list of metals in order of their reactivity.
• Galvanic cell: an electrochemical cell that generates electricity through the corrosion of metal.

Other Key Concepts

• Crystal lattice: a three-dimensional arrangement of points in a crystal.
• Lattice energy: the energy required to separate the ions in a crystal lattice.
• Ionic bond: formed by the transfer of electrons between atoms to form ions.
• Covalent bond: formed by sharing of electrons between atoms.
• Electrolysis: the process of separating ions in a solution using an electric current.Here are the study notes for the provided text:
• Corrosion*
• Sacrificial anodic metal: Zinc
• Volatile oxide corrosion product of metal: MoO3
• Standard electrode potential of Zn2+/Zn: -0.76V
• Standard electrode potential of hydrogen: 0.00V
• Zinc is more electropositive than iron
• Metals that form unstable metal oxides: Cr, Na, Ag, Mo
• Passivity is due to the formation of an adhering oxide film
• Galvanic Cells*
• Primary cell: Alkaline cell or Laclanche cell
• Coating of Zn, Al, & Cd on steel: Cathodic
• Oxygen absorption mechanism of metal is observed in: Acidic, basic, and neutral medium
• Metal at the bottom of galvanic series: Most active
• Strong electrolyte: HCl, HNO3, H2SO4
• Electrolysis*
• 1 Faraday: 96500 Coulomb
• Electro refining of metal: Purification of metal
• Process of coating one metal on another metal by electrolysis: Electroplating
• Coating of Tin on iron by hot dipping process: Tinning
• Numericals*
• Calculate electrochemical equivalent and chemical equivalent of copper
• Calculate time in seconds in which 0.3 gm of copper is liberated
• Calculate the equivalent weight of metal
• Calculate the strength of the current
• Paints and Varnishes*
• Purpose of painting an iron grill: To protect it from corrosion
• A good paint must have: High covering power, brushing characteristics, light reflecting property
• Constituents of paint: Fillers, pigment, drying oil
• Varnish is used to give: Transparent finish
• Thinner is added to paint to: Reduce the consistency
• Insulators*
• Insulators are classified on the basis of: Manufacturing, state of occurrence, application
• Materials used as insulators: Glass wool, thermocole, asbestos, iron
• Properties of insulators: Low thermal conductivity, low electrical conductivity
• Good thermal insulators should have: Low thermal conductivity
• Polymers and Monomers*
• Polyethylene is formed by: Polymerization
• Types of polymerization: Addition, condensation
• Structural unit of a high polymer: Monomers
• Commercial name of phenol-formaldehyde resin: Bakelite
• Bakelite is prepared by the condensation of: Phenol and formaldehyde
• Bakelite is a cross-link polymer
• Adhesives*
• Adhesive is a substance used: For sticking two unlike bodies together
• Example of vegetable glue: Soybean glue
• Example of inorganic adhesive: Sodium silicate
• Araldite is a: Thermosetting resin
• Natural adhesive used in stamps, envelops, etc.: Gum
• Lubricants*
• Graphite is a: Solid lubricant
• Lubricating helps to: Minimize wear in moving parts
• Viscosity index is a measure of change of viscosity with change in: Temperature
• A liquid lubricant should possess: High oiliness, moderate viscosity### Types of Oils
• Tallow oil, coconut oil, olive oil, and palm oil are examples of different types of oils.

Preparation of Grease

• Grease is prepared by a process called saponification.
• Saponification involves the use of oil, not solid lubricants or fatty acids with oil.
• Oil is the primary component used in the preparation of grease.