This reaction produces a precipitate at the end of the reaction. A precipitate is an insoluble solid that settles at the bottom of the reacting solution. For example,
Pb(NO3)2(aq) + 2KI(aq) PbI2(s) + 2KNO3(aq)
When lead nitrate (Pb (NO3)2) is mixed with potassium Iodide (KI), there is the formation of a precipitate as a result of potassium iodide (PbI2) being formed. In the reaction above, (aq) denotes aqueous while (s) denotes a solid. Another example is
BaCl2 (aq) + K2SO4 (aq) BaSO4 + 2KCl
In this second example, when BaCl2 is mixed with K2SO4, there is formation of a white precipitate due to formation of barium sulphate ( BaSO4).
This is a reaction that takes place when acid reacts with water, leading to the formation of salt and water only. Acids have free hydrogen ions H+ ions; however, acids have free --OH in them when they react; the hydrogen combine with the hydroxyl ion to form water.
Example:
HCl(aq) + NaOH(aq) H2O(l) + NaCl(aq)
In this example, the initial reaction has been broken down into its constituent parts. The spectator ions (the ions common on both parts of the equation) will then cancel each other out. The following is the final equation showing the formation of water:
H+(aq) + OH-(aq) H2O(l)
In this type of aqueous equation, oxidation and reaction takes place in the same solution. As one product is being oxidized, the other is reduced.
Example:
2Na(s) + Cl2 (g) 2NaCl(s)
In the example above, on the left-hand side of the reaction, sodium has a charge and the same is true for chlorine. On the right-hand side of the equation, sodium has a charge of one and chlorine negative one. Sodium has been oxidized whereas chlorine has been reduced.
An ionization reaction is where solutions dissolve in water resulting in the formation of solvated ions. Ionization reactions are further divided into single-replacement reactions and double-replacement reactions. Ionization reactions depend on the level of ionization present in the dissolving mixture whether it is a strong or a weak ionizer.