Double replacement reactions are the result of specific forces. These include the creation of a solid, gas or weak ionizing liquid. As the two active compounds are brought together, these matter states change into a solid, such as salt. Gas state changes can be visible, forming bubbles in the mixture. Liquid state changes are the least visible, especially when the resulting reaction occurs in a water medium.
During a double replacement reaction, two compounds come together. Each exchanges one element from its compound, resulting in two new compounds. For instance, in the case of compound AB mixing with compound CD, the result is AX + BY -> AB + XY. This exchange relies on the ionization of each compound, allowing each element to create new bonds within the mixture. This reaction can seem violent, especially when two of elements combine rapidly, forming a gas result.
A cation is a positively charged ion, or an ion with additional electrons. A cation has a natural attraction to anions, as the combination of the two stabilizes the charges of both. An anion is a negatively charged ion, or an ion with fewer than normal electrons. When two charged compounds come together, this particle ionization creates the attraction between the cations of each compound and the anions of the other. This attraction is powerful enough to split the compounds and create the pull, which forms the new compounds. This ionization process is the explanation for how double replacement reactions occur both in nature and during experiments.
Double replacement reactions are commonly written in simple notation, such as AgNO3 (liquid) + KCl (liquid) -> AgCl (solid) + KNO3 (liquid). While the concept of writing double replacement reactions is understood, the actual reaction between two charged compounds requires experimentation to determine the actual effect. Scientists combine compounds in a safe laboratory environment, determining which compounds will create a double replacement reaction. You can make predictions by reviewing the notation and determining the normal state of a compound. For example, AgCl s normally found in a solid state, which qualifies for the matter state change-driving force for the reaction. Testing is still required to ensure the prediction is correct.