Precipitation reactions usually have two ionic compounds as the reactants and two different ionic compounds as the products. One of the products will be insoluble. Precipitation reactions usually take the following form:

AX(aq) + DE(aq) → DX(aq) + AE(s)

You can predict the formula for the products of ionic compounds. Remember that opposite charges attract; therefore, the ionic compounds will always be made up of a positive ion and a negative ion.

Interactive exercise. Assistance may be required. Let’s return to the first example of a precipitation reaction to practice predicting products and writing equations. Use the diagram below to guide you.

Interactive exercise. Assistance may be required. Complete the equations below.