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🧪 Chemistry  ·  Surface Chemistry  ·  NEET & JEE

Why does activated charcoal adsorb gases more effectively than ordinary charcoal?

Answer: It has a much larger effective surface area due to its porous structure.

  • A It actually has a smaller exposed surface area than ordinary charcoal
  • B It has a much larger effective surface area due to its porous structure
  • C It chemically reacts with essentially every gas it comes into contact with
  • D It carries a fixed negative surface charge that electrostatically attracts gas molecules

Correct answer: B. It has a much larger effective surface area due to its porous structure

Explanation: Activation increases the porosity of charcoal, dramatically increasing its surface area and therefore its adsorption capacity.

Adsorption Isotherm: x/m vs PressureP (pressure)x/mlow P: x/m ∝ Phigh P: saturation plateauAt high pressure, all surface sites are occupied - the curve flattens (monolayer saturation)

A typical adsorption isotherm: x/m (mass adsorbed per gram of adsorbent) rises steeply at low pressure, then flattens into a saturation plateau as the adsorbent surface fills up.

Concept context

Explore the chemistry that happens at interfaces, from catalysts that speed up industrial reactions to colloids like milk, smoke, and gels that surround us every day.

Read the full Surface Chemistry notes →