Nanochemistry: Important Two Marks Questions and Answers

UNIT 2: Nanochemistry

Two Marks Questions and Answers

1. Define nanoscience.

Nanoscience is defined as the study of phenomena and manipulation of materials at atomic, molecular and macromolecular scales.

2. What are nonoparticles?

Nanoparticles are the particles, the size of which ranges from 1‒100 nm.

3. What are nano‒materials? (or) Define nono materials.

Nanomaterials are the materials having components with size less than 100 nm at least in one dimension.

4. What is nano‒chemistry?

Nano‒chemistry is the branch of nano‒science, which deals with the chemical applications of nanomaterials. It also includes the study of synthesis and characterisation of nanomaterials.

5. What are the types (or) categories of nanomaterials.

Types (or) Categories of nano‒materials:

0 ‒ dimension Co‒ordinates ‒ Examples: Nanoclusters

1‒dimension Co‒ordinates ‒ Examples: Nanotubes, nanowires, nanorods

2‒dimension Co‒ordinates ‒ Examples: Graphene, mxenes, thin films and surface coatings

3‒dimension Co‒ordinates ‒ Examples: Precipitates, colloids, bulk, powders, bundles of nanotubes and wires

6. Illustrate the size‒dependent properties of nanoparticles.

We know that the finely ground materials (nano particles) have larger surface area when compared to same mass of the bulk materials. A larger number of atoms reside at the grain boundaries of nano particles, which affect the properties like melting point, density, ductility, mechanical and chemical properties.

7. Name some important physical methods of synthesising nano‒materials.

(i) Laser ablation

(ii) Chemical Vapour Deposition (CVD)

(iii) Electro‒deposition

8. What is CVD?

CVD is Chemical Vapour Deposition. It is a process of chemically reacting a volatile compound of a material with other gases, to produce a non‒volatile solid that deposits automatically on a suitably placed substrate.

9. What is the basic principle involved in solvothermal of nano‒materials.

Solvothermal synthesis involves the use of solvent under high temperature (between 100°C to 1000°C) and moderate to high pressure (1 atm to 10,000 atm) that facilitate the interaction of precursors during synthesis.

10. Write the principle involved in the sol‒gel process

(or)

Give a brief description about the sol‒gel principle.

Sol‒gel process is a method of producing solid materials from small molecules. In this method, the precursor is dissolved in water (or) alcohol to form “sol" and then converted to gel like structure by heating.

It is a wet chemical technique. Generally, it is used to produce metal oxides.

It involves the following steps

(i) Preparation of monomers

(ii) Formation of Sol

(iii) Formation of Gel

(iv) Aging process

(v) Drying

(vi) ) Tempering (Heating)

11. Define nano‒wires.

Nano‒wire is a material having an aspect ratio ie., length to width ratio greater than 20. Nano‒wires are also referred to as "quantum wires".

12. What are the characteristics of nano‒wires.

(1) Nano‒wires are one‒dimensional material.

(ii) Conductivity of a nano‒wire is less than that of the corresponding bulk materials.

(iii) It exhibits distinct optical, chemical, thermal and electrical properties due to this large surface area.

13. Mention some important applications of nano‒wires.

(i) Nanowires are used for enhancing mechanical properties of composites.

(ii) It is also used to prepare active electronic components such as p‒n junction and logic gates.

(iii) Semiconductor nanowire crossings are expected to play a important role in future of digital computing.

14. What is nano‒rod?

Nano rod is one dimensional cylindrical solid material having an aspect ratio i.e., length to width ratio less than 20.

15. What are nanoclusters?

Nanoclusters are fine aggregates of atoms (or) molecules. The size of which ranges from 0.1 to 10 nm. Of all the nano materials, nanoclusters are the smallest sized nano materials because of their close packing arrangement of atoms.

16. What are nano composites?

Nano composites are a class of nanomaterials where in one (or) more nanoparticles are embedded in a ceramic, metal (or) polymer matrix.

(or)

The polymer matrix reinforced by a nanomaterials is called nano composites.

17. What is magic number

It is the number of atoms in the clusters of criticle sizes with higher stability.

18. What are carbon nano‒tubes.

Carbon nanotube is a tubular form of carbon with 1‒3 nm diameter and a length of few nm to microns.

19. Mentin some uses of CNTs.

1. It is used in battery technology and in industries as catalyst.

2. It is also used as light weight shielding materials for protecting electronic equipments.

3. CNTs are used effectively inside the body for drug delivery.

4. It is used in composites, ICs.

20. Mention some characteristic properties of nanomaterials.

(i) Nanomaterials are very strong and withstand extreme strain and tension.

(ii) It possesses very good electrical properties and thermal conductivity.

21. List any four nano‒materials.

(i) Carbon nanotubes.

(ii) Nanowire.

(iii) Qauntum dots.

(iv) Dendrimers.

22. What is meant by top‒down and bottom‒up process?

(i) Top‒down process

Top‒down process involves the conversion of bulk materials into smaller particles of nano‒scale structure.

(ii) Bottom‒up process

Bottom‒up process involves building‒up of materials from the bottom by atom by atoms, molecule by molecule (or) cluster to the nanomaterials.

23. Define electrospinning process.

Electrospinning is a method of producing ultrafine (in nanometers) fibres by charging and ejecting a polymer solution through a spinneret under high‒voltage electric field and to solidify (or) coagulate it to form a filament.

24. What are the applications of electrospinning process?

(i) Electrospinning is used in diagnosis and treatment of diabetes.

(ii) Electrospun fibres are used in energy storage devices such as, solar cell, fuel cell, super capacitors.

(iii) It is also used in textiles for smart clothing, protecting clothing and fire retardant fibres.

25. Name an nanoparticle used in targeted drug delivery.

Gold nano particles

26. What is the main function of nano‒medibots?

It releases anti‒cancer drug and treat cancer.

27. What is the main function of nanosensors in agriculture?

It identifies diseases in crop production.

28. Which nanoparticles are used to electrolyse hydrogen from sea water?

Thin film of nickel selenide.

29. What is the role of nanotechnology in electrical wires?

The wire containing carbon nanotubes reduces resistance.

30. What is the main role of quantum wires?

It improves electrical conductivity.

31. Comment on nanoparticles are highly effective.

They are effective due to

(i) huge surface area

(ii) enhanced reactivity.

32. Name an nanoparticle acting as photocatalyst.

Titania‒based nanocrystals.

33. What is the main catalyst used in bio‒diesel production?

KF/CaO nano catalyst