Video Transcript
Tubes A, B, C, and D contain, respectively, potassium fluoride, potassium chloride, potassium bromide, and potassium iodide. On adding fluorine to the tubes, which tube or tubes will most likely show a chemical reaction?
The question tells us that each of the tubes contains a different potassium halide. We need to determine what will happen when fluorine is added to each of the tubes. Fluorine, chlorine, bromine, and iodine are all halogens found in group seven A of the periodic table. Halogens can react with compounds via a displacement reaction.
A displacement reaction is a chemical reaction in which one reactant displaces part of another reactant. In a halogen displacement reaction, a more reactive halogen displaces a less reactive halogen in a compound. The reactivity of the halogens decreases down the group. So fluorine is the most reactive halogen. It can displace any halogen in a compound that is less reactive.
Chlorine, bromine, and iodine are less reactive than fluorine. So when fluorine is added to potassium chloride, potassium bromide, or potassium iodide, the fluorine can displace the less reactive halogen to form potassium fluoride. Therefore, when fluorine is added to tubes B, C, and D, a chemical reaction will occur. Fluorine will not replace the fluoride ions in potassium fluoride as they are the same element and have the same reactivity.
Therefore, all tubes except A will most likely show a chemical reaction when fluorine is added.
