WJEC Chemistry Practice Exam 2025 – The Complete All-in-One Guide to Exam Success!

The type of reaction that involves the exchange of elements between compounds is the double replacement reaction. In this type of reaction, two compounds react and their positive and negative ions exchange partners, forming two new compounds. This often occurs in solutions where ionic compounds dissociate into their respective ions.

For instance, if you have two solutions of ionic compounds, such as silver nitrate and sodium chloride, the sodium ions and silver ions would exchange places, resulting in the formation of sodium nitrate and silver chloride. This process is driven by the formation of a precipitate, gas, or water in the products.

Understanding the mechanisms of double replacement reactions is foundational in predicting the products when two ionic compounds are mixed. Recognizing this allows for insight into many practical applications in chemistry, such as those seen in titrations and precipitation reactions.