Physical Chemistry Assignment

Surface Area and Pore Size Analysis

1.                The adsorption isotherm for nitrogen on 1.00 g of mesoporous silica gel at 77K is shown in the figure below.  Explain with reference to the Kelvin or other equations how a consideration of the pore shape accounts for the observed hysteresis loop.

(10 marks)

2.                The hysteresis loop is characterised between lower and upper points given by

p/p0 = 0.80, V = 166 cm3 N2 (STP) and p/p0 = 0.93, V = 879 cm3 N2 (STP)

Determine;

i.an estimate of the specific surface are of the sample (B point method)

ii.the  upper and lower values of the true pore radii

iii.the total pore volume of the sample

iv. an estimate of the density of the silica sample

(non-porous silica typically has density r = 2.65 g cm-3)

(20 marks)

(DATA: For Liquid nitrogen s = 0.35 nm, Vm(l) = 34.7 cm3 mol-1, g = 8.85 mNm-1

Area occupied by a nitrogen molecule = 16.20 × 10-20 m2 STP = 0°C, 101325 Pa)

3.                Write a fully referenced account of the background theory and experimental procedure for the determination of pore size (diameter and volume) using the technique of  mercury porosimetry.  Discuss the major differences – advantages or disadvantages of this technique in comparison to gas adsorption methods.  Use diagrams as necessary.

(20 marks)

B)   Further Guidance

PLACE THIS ORDER OR A SIMILAR ORDER WITH US TODAY AND GET A GOOD DISCOUNT