# Which substance can be easily adsorbed by charcoal?

Which substance can be easily adsorbed by charcoal?

1. $$\ce{CO2}$$
2. $$\ce{SO2}$$
3. $$\ce{H2}$$
4. $$\ce{He}$$

I thought the answer was (3) because the intermolecular forces are weak. So charcoal can easily adsorb hydrogen. But answer given is (2) which has strong intermolecular forces. Is my reasoning wrong?

• The adsorption occurs because of the intermolecular forces, not despite them. – Ivan Neretin Mar 6 '16 at 10:57

## 1 Answer

Gas molecules bind to activated carbon as a result of London dispersion forces. Therefore, the larger the molecules, as determined by the size and the number of atoms in it, the better they bind to the carbon.

If you were to rank these in order of highest dispersion forces to lowest, that list would read: $$\ce{SO2>CO2>H2>He}$$