MChem Master of Chemistry Materials Chemistry

Question 1

What defines a zeolite's selectivity as a molecular sieve or catalyst?

Accepted Answer

Its regular microporous aluminosilicate framework with defined pore sizes

Answer

Zeolites are crystalline aluminosilicates with uniform micropores (3–10 Å) that selectively admit molecules by size and shape, making them ideal sieves and acid catalysts.

Question 2

What is the key characteristic of a thermosetting polymer compared to a thermoplastic polymer?

Accepted Answer

Thermosets form irreversible cross-linked networks during curing and cannot be remelted

Answer

Thermosetting polymers (epoxies, phenolics) form covalent cross-links during curing, creating an infusible, insoluble network that cannot be reprocessed.

Question 3

In the context of nanomaterials, what phenomenon explains why gold nanoparticles appear red/purple rather than gold-colored?

Accepted Answer

Localized surface plasmon resonance (LSPR)

Answer

LSPR occurs when the collective oscillation of conduction electrons in gold nanoparticles resonantly absorbs visible light (~520 nm), producing red/purple color.

Question 4

What is the role of a surfactant in the synthesis of mesoporous silica materials (e.g., MCM-41)?

Accepted Answer

It serves as a structure-directing template around which silica condenses

Answer

Surfactant micelles act as structure-directing agents; silica condenses around them, and template removal (calcination) leaves ordered mesopores with high surface area.

Question 5

What distinguishes Type II superconductors from Type I superconductors?

Accepted Answer

Type II allow partial magnetic flux penetration in the mixed state between two critical fields

Answer

Type II superconductors have two critical fields (Hc1 and Hc2); between them, magnetic flux penetrates as quantized vortices, enabling their use at higher fields.

MChem Master of Chemistry Practice Test

MChem Master of Chemistry Practice Test

MChem Master of Chemistry Materials Chemistry