Porous Frameworks: Pores, Guests and Stability · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.
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Solids built around empty space

Science · Chemistry · ages 22-23
Name ______________________   Date ____________

  1. An adsorption isotherm reaches a saturation plateau reported in mmol/g. What does that reported value directly measure?

    • The saturated amount adsorbed per sample mass
    • The geometric pore volume without any conversion
    • The energy of each adsorption interaction directly

  2. Which feature provides internal space that guests can enter to reach adsorption surfaces?

    • Accessible pores inside the framework
    • Blocked cavities with sealed pore openings
    • External crystal surfaces without internal access

  3. Supercritical drying can reduce the risk of capillary-stress collapse during solvent removal.

    Circle one:   True   False

  4. A framework loses uptake after ordinary solvent drying. Which structural change could reduce accessible pore space?

    • Solvent removal created additional accessible cavities
    • The walls became more rigid without blocking any pores
    • Capillary stress collapsed the pore network

  5. Two similarly sized gases can both enter a framework. If dipole interactions dominate, which design is most likely to favour adsorption of the polar gas?

    • Wider openings with no change to surface chemistry
    • Accessible pores with a polar internal surface
    • Thicker external walls with no change inside the pores

  6. Saturated uptake is 1.5 mmol/g. The guest molar mass is 30 g/mol. Assuming adsorbed-phase density 0.60 g/cm3, what pore-volume estimate follows?

    • 0.025 cm3/g
    • 0.075 cm3/g
    • 0.750 cm3/g

  7. You want high methane uptake at low pressure. Which is the best starting design to test, rather than a guarantee of usable storage capacity?

    • Accessible methane-sized pores with attractive walls
    • The widest possible pores regardless of guest interactions
    • The least costly nodes regardless of pore access or stability

  8. A proposal claims longer linkers must improve low-pressure storage of a small gas. Which limitation should be checked?

    • Longer linkers guarantee identical topology and higher affinity
    • Linker changes cannot affect either pore geometry or stability
    • Larger pores may weaken confinement or reduce stability
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Solids built around empty space W1-mt_csqPeYIhN6-s1

  1. The saturated amount adsorbed per sample mass · mmol/g reports adsorbed amount per sample mass. A volume estimate also needs a conversion and an assumed adsorbed-phase density.
  2. Accessible pores inside the framework · Accessible pore openings let guests enter internal cavities and reach surfaces where adsorption can occur.
  3. True · Supercritical drying avoids a liquid-vapour interface and can reduce capillary stress. It does not prevent every possible form of framework damage.
  4. Capillary stress collapsed the pore network · Collapse can reduce accessible pore space. Lost uptake alone does not establish that collapse occurred.
  5. Accessible pores with a polar internal surface · Under the stated interaction regime, a polar internal surface can favour the polar guest. Separation still requires testing.
  6. 0.075 cm3/g · Convert to 0.0015 mol/g, multiply by 30 g/mol, then divide 0.045 g/g by 0.60 g/cm3.
  7. Accessible methane-sized pores with attractive walls · Suitable confinement and attractive interactions can help low-pressure uptake. Methane is nonpolar, and usable storage also requires gas release.
  8. Larger pores may weaken confinement or reduce stability · Longer linkers do not guarantee the desired network or uptake. Larger pores can weaken confinement and make some frameworks less stable.
Worksheet · LightMySky