Investigating the reactions of halogens and their compounds.

Investigating the reactions of halogens and their compounds

A) When bromine solution is added to cyclohexane, two layers are formed. The top layer is orange and the bottom layer is yellow. Non soluble solvent cyclohexane layer is at the top. Two layers of solution are formed because cyclohexane is non-polar and bromine is polar so they don’t mix, this is immiscible. Cyclohexane is less dense than water so it is at the top.

Bromine added to cyclohexane solution turns orange because the aqueous layer of bromine moves to the cyclohexane layer.

B) When halogen solution is added to solutions of potassium halides followed by the addition of cyclohexane to the mixture two layers of solution is always formed. For example when chlorine solution is added to potassium bromide solution followed by cyclohexane, the upper layer is light brown/ orange and the bottom layer is light yellow. The top layer becomes orange because the chlorine displaces the bromine because chlorine is more reactive than bromine. Chlorine added to cyclohexane and potassium chloride solution turns orange because the aqueous layer of chlorine moves to the cyclohexane layer.

Chlorine is highly electronegative; they form ionic compounds with polar bonding. As you go down group seven electronegativity decreases.

The equation for this reaction is:

Cl2 (aq) +2K+I- (aq) 2K+Cl- (aq) + I2

This is a redox reaction, this is because Cl oxidises I- (oxidation state –1) to iodine (oxidation state 0). Chlorine, Cl2 (oxidation state 0 ) is reduced to Cl- (oxidation state –1). So the more reactive halogen (Cl) will oxidise the halide ions of a less reactive one (Br). The other equation for the reaction are:

Cl2 (aq) +2K+Br- (aq) ...