solution

The following data were obtained in a BET apparatus for adsorption equilibrium of N2 on silica gel (SG) at -195.8°C. Estimate Sg in m2/g of silica gel. How does your value compare with that in Table 15.2?

N, Partial Pressure, torr Volume of N, Adsorbed in cm3 (0°C, 1 atm) per gram SG 6.0 24.8 140.3 230.3 285.1 320.3 430 505 6.1 12.7 17.0 19.7 21.5 23.0 27.7 33.5 Table 15.2 Representative Properties of Commercial Porous Adsorbents Capacity for H2O Vapor at 25°C and 4.6 mmHg, wt% (Dry Basis) Pore Diameter d», Ã… 10–75 Particle Density Pp, g/cm Particle Porosity, , Surface Area Sg, m²/g Adsorbent Nature 0.50 1.25 320 Hydrophilic, amorphous Hydrophilic/hydrophobic, amorphous 22–26 100–150 0.47 0.71 1.09 0.62 750–850 300-350 11 Hydrophobic, amorphous Activated alumina Silica gel: Small pore Large pore Activated carbon: Small pore Large pore Molecular-sieve carbon Molecular-sieve zeolites Polymeric adsorbents 0.4-0.6 Hydrophobic Polar-hydrophilic, crystalline Hydrophilic to hydrophobic 10–25 >30 2–10 3–10 30–400 – 0.2-0.5 0.4-0.55 0.5-0.9 0.6-0.8 0.98 1.4 0.3-1.0 400–1200 200-600 400 600–700 50–700 20–25