Silica Gel may be regarded as a typical polar sorbent. The relative adsorptivity of different molecular groups or substitutes on silica gel is similar to that observed for other polar adsorbents. The silica gel surface is weakly acidic and there is a tendency towards preferential adsorption of strongly basic substances relative to adsorption on neutral or basic adsorbent. It also finds application in reversed phase partition chromatography. This adsorbent with empirical formula SiO2.xH20 is described variously in literature as silica, silica gel, silicic acid and these terms are essentially synonymous.