GATE-CH-1993-22-b-mt-5mark

The equilibrium water adsorbed by a certain silica gel in contact with moist air varies linearly with the humidity of air as, \[ Y = 3.4435 \times 10^{-2} X \] where
\(X\) = kg water adsorbed / kg dry gel, and
\(Y\) = humidity of air kg moisture / kg dry air.

0.5 kg of silica gel containing 5% (dry basis) adsorbed water is placed in a collapsible vessel in which there are 10 m\(^3\) of moist air, partial pressure of water being 15 mm Hg. The total pressure and temperature are kept at 1 std atm and 25\(^\circ \)C respectively.
(i) What is the amount of water (in gram) picked up from the moist air in the vessel by silica gel?
{#1}

(ii) What is the final partial pressure of water vapor (in mm Hg) in the vessel?
{#2}

GATE-CH-2004-67-mt-2mark

At equilibrium, the concentration of water in vapor phase \((C^*)\) in kg/m³ of air space and the amount of water (\(m\)) adsorbed per kg of dry silica gel are related by \(C^* = 0.0667\;m\). To maintain dry conditions in a room of air space 100 m³ containing 2.2 kg of water vapour initially, 10 kg of dry silica gel is kept in the room,. The fraction of initial water remaining in the air space after a long time (during which the temperature is maintained constant) is

• 0.0

• 0.2

• 0.4

• 1.0

GATE-CH-2016-45-mt-2mark

At 30^oC, the amounts of acetone adsorbed at partial pressures of 10 and 100 mm Hg are 0.1 and 0.4 kg acetone/kg activated carbon, respectively. Assume Langmuir isotherm describes the adsorption of acetone on activated carbon. What is the amount of acetone adsorbed (in kg per kg of activated carbon) at a partial pressure of 50 mm Hg and 30^oC?

• 0.23

• 0.25

• 0.30

• 0.35

GATE-CH-2015-45-mt-2mark

Adsorption on activated carbon is to be used for reducing phenol concentration in wastewater from 0.04 mol/litre to 0.008 mol/litre. The adsorption isotherm at the operating temperature can be expressed as \(q=0.025C^{1/3}\); where \(q\) is the phenol concentration in solid (mol/g solid) and \(C\) is the phenol concentration in water (mol/litre). The minimum amount of solid (in grams) required per liter of wastewater (up to one decimal place) is ____________

• Answer