* Reactivity Trend: Halogens (Group 17) become less reactive as you move down the group. This is because the outermost electrons are further from the nucleus, making it harder to gain an electron to form a negative ion.
* Chlorine vs. Bromine: Chlorine is more reactive than bromine. This means that chlorine has a stronger tendency to gain electrons and form negative ions (Cl-) compared to bromine.
* Displacement Reaction: When chlorine is added to a potassium bromide solution, the more reactive chlorine atoms displace the less reactive bromine atoms.
* Chlorine atoms gain electrons from bromide ions (Br-), forming chloride ions (Cl-)
* Bromine atoms lose electrons, becoming elemental bromine (Br2).
* Reaction Equation: The overall reaction is:
* Cl2(g) + 2KBr(aq) → 2KCl(aq) + Br2(l)
Key Points:
* The displacement reaction occurs because chlorine is more reactive than bromine.
* The reaction is a single displacement reaction.
* The presence of potassium ions (K+) in the solution is not directly involved in the displacement process. They simply act as spectator ions.
In summary, the displacement of bromine by chlorine is driven by the higher reactivity of chlorine compared to bromine. This leads to chlorine gaining electrons and forming chloride ions, while bromine loses electrons and becomes elemental bromine.
