Question

The reaction of a metal, M, with a halogen, X₂, proceeds by an exothermic reaction as indicated by this equation: M(s)+X₂ (g)⟶MX₂(s). For each of the following, indicate which option will make the reaction more exothermic. Explain your answers.

a) Using a smaller metal, M.

b) Using a larger metal, M.

c) Using a more reactive halogen, X.

d) Using a less reactive halogen, X.

Answer 1

Using a larger metal M typically leads to a more exothermic reaction due to lower ionization energy, and using a more reactive halogen X also makes the reaction more exothermic because of higher electron affinity. Conversely, smaller metals and less reactive halogens would result in less exothermic reactions.

Step-by-step explanation:

The reaction of a metal, M, with a halogen, X₂, to form a metal halide, MX₂, can be influenced by several factors.

• Using a larger metal, M: A larger metal ion typically has a lower ionization energy, which means it requires less energy to remove an electron and form a cation. A lower ionization energy can lead to a more exothermic reaction since less energy is put in to remove electrons from the metal.
• Using a more reactive halogen, X: A more reactive halogen has a higher electron affinity, which releases more energy when it gains an electron to form a halide ion. This can make the reaction more exothermic.

Conversely, using a smaller metal M or a less reactive halogen X would generally result in a less exothermic reaction, as smaller metals have higher ionization energies and less reactive halogens have lower electron affinities.