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# BHS Chemistry 2024/25 ## Solubility of the Halogens Halogens are non-polar molecules, so they are sparingly soluble in water, but more soluble in non-polar solvents like hexane. If a halogen is present in a large volume of water, it can be identified by shaking with hexane. The halogen transfers...

# BHS Chemistry 2024/25 ## Solubility of the Halogens Halogens are non-polar molecules, so they are sparingly soluble in water, but more soluble in non-polar solvents like hexane. If a halogen is present in a large volume of water, it can be identified by shaking with hexane. The halogen transfers to the hexane layer, and the upper hexane layer may become intensely colored if allowed to settle. | | Color in non-aqueous solvent (e.g., hexane) | Color in water | |---|---|---| | Cl2 | Colourless | Colourless | | Br2 | Orange | Orange | | I2 | Violet | Brown | ## Displacement Reactions of Halogens The reactivity of halogens decreases down the group. | Reaction with excess: | Cl2(aq) (almost colorless) | Br2(aq) (Orange) | I2(aq) (brown) | |---|---|---|---| | KCl(aq) (colorless) | Br2 + 2KCl → | No color change | I2 + 2KCl → | | KBr(aq) (colorless) | Cl2 + 2KBr → Br2 + 2KCl colorless → orange| Br2 + 2KBr → | No color change | | KI(aq) (colorless) | Cl2 + 2KI → I2 + 2KCl colorless → brown | Br2 + 2KI → I2 + 2KBr orange → brown| I2 + 2KBr → | As reactivity decreases down the group, more reactive halogens will replace less reactive halogens from their halides. At the top of the group, halogens are better oxidizing agents. (Cause things to lose electrons). OIL