In this post, you will get the lubricants chapter questions and answers (short questions and answers) of the Applied Chemistry or Engineering Chemistry Book of Diploma or Polytechnic Engineering Students and B.Tech. Engineering 1st Year Students. In the post we have many short questions and their answers of lubrication chapter. Students have to go through this to score better in final exam because these questions are very important.
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Lubricants Chapter Questions and Answers | Applied Chemistry for Engineering 1st Year Students
What is a lubricant? Define lubricant with example.
A lubricant is a substance that reduces friction between two moving surfaces.
Example: Engine oil, grease, graphite.
What are the main functions of a lubricant?
Functions of lubricants include:
A. Reducing friction and wear
B. Preventing rust and corrosion
C. Cooling engine or machinery parts
D. Cleaning away dirt or metal particles
E. Sealing gaps between moving parts
Why are lubricants used in machines and engines?
Lubricants are used to reduce friction, improve efficiency, prevent wear and tear, and extend the life of machinery.
Name one solid lubricant and write its use.
Example: Graphite or Molybdenum disulphide (MoS₂)
Use: Applied in high-temperature or heavy-load machinery where liquid lubricants fail.
What is grease in chemistry?
Grease is a semi-solid lubricant made by mixing lubricating oil with a thickening agent such as calcium or lithium soap. It is used where liquid lubricants cannot stay in place.
How are lubricants classified? Give examples.
Types of lubricants:
1. Liquid lubricants: Mineral oil, synthetic oil
2. Semi-solid lubricants: Grease
3. Solid lubricants: Graphite, MoS₂
What are synthetic lubricants? Give two examples and their uses.
Synthetic lubricants are man-made oils designed for high performance.
Examples:
Silicone oil – used in jet engines
Ester-based oil – used in aircraft and high-speed machines
How do you select a suitable lubricant for a machine?
Lubricant selection depends on:
A. Operating temperature and load
B. Speed of machine
C. Type of motion (sliding, rolling, etc.)
D. Environmental conditions (dust, moisture, etc.)
What additives are used to improve the quality of lubricants?
Common additives:
1. Antioxidants
2. Detergents and dispersants
3. Corrosion inhibitors
4. Anti-wear agents
5. Viscosity index improvers
How do additives improve the quality of lubricants?
Additives enhance performance by reducing oxidation, foaming, and corrosion, maintaining viscosity, and improving lubrication under extreme conditions.
How can the effectiveness of a lubricant be improved?
Effectiveness can be improved by:
1. Using proper additives
2. Maintaining cleanliness and correct viscosity
3. Regular replacement and filtration
What are flash point and fire point of lubricants?
Flash point: The lowest temperature at which oil vapors ignite momentarily.
Fire point: The temperature at which oil burns continuously for at least 5 seconds.
What are the uses of grease?
Grease is used in:
1. Ball bearings and roller bearings
2. Gears and joints
3. Places where continuous lubrication is difficult
Name two common lubricants and mention their uses.
Engine oil: Used in automobile engines.
Gear oil: Used in gearboxes and transmission systems.
Give examples of two synthetic lubricants and their uses.
Silicone oil: Used in jet engines and high-temperature machines.
Ester-based lubricant: Used in aircraft turbines and racing vehicles.
Name one solid lubricant used in industries.
Graphite – used in locks, high-temperature, and high-pressure machinery.