What type of reaction is fes + 2 hcl > fecl2 + h2s?

Double replacement means a reaction that includes two molecules that each have two different ions. After the reaction, the ions pairs have switched, which is what is shown in the above equation. A single replacement would be a very simple reactions such as: 2Fe(II)S + Ov2^2- -> 2Fe(II)O + 2S^2- A decomposition reaction would be shown as this: 2NaCl -(dissolve in water)> 2Na^+ + Clv2^- A synthesis reaction could be the exact opposite: 2Na^1+ + Clv2^1- -> 2NaCl