Aqueous silver nitrate solution, AgNO 3(aq), contains silver ions, Ag + (aq), and nitrate ions, NO 3 - (aq).Aqueous sodium chloride solution, NaCl (aq), contains sodium ions, Na + (aq), and chloride ions, Cl - (aq).We can work out the possible products of the reaction by looking at the species present in each solution: Spectator ions are not included in the equation:Ĭonsider the reaction between aqueous solutions of sodium chloride, NaCl(aq), and silver nitrate, AgNO 3(aq). Only the reactants and product taking part in the formation of the precipitate are written in the equation, the reactants as ions, the product as a molecule. Chemical equations written to represent precipitation reactions can be written in one of three ways 3:Īll reactants and products are written as if they are molecules:Įxample: AB (aq) + CD (aq) → AD (aq) + CB (s)Īll reactants and products that are soluble are written as ions, only the precipitate is written as if it were a molecule:Įxample: A + (aq) + B - (aq) + C + (aq) + D - (aq) → A + (aq) + D - (aq) + CB (s).States of matter must be included in the chemical equation for a precipitation reaction:.Spectator ions do not participate in precipitation, they 'watch' the action like spectators watching sport. Spectator ions are ions in solution that are not used to form the precipitate.A precipitation reaction is a chemical reaction which produces a precipitate when solutions are mixed together.

Solubility Rules can be used to predict if a product will be insoluble (forms a precipitate) 2 in aqueous solutions at 25☌

A precipitate is an insoluble 1 solid that forms when solutions are mixed.

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Remember, a balanced net ionic equation only describes chemical species that participate in the reaction.

Indicate solid with (s), liquid for (l), gas with (g), and an aqueous solution with (aq).

Be sure to indicate the state of each species.

Do this for both sides of the equation and combine H + and OH - ions to form H 2O.

If the reaction takes place in a basic solution, add an equal number of OH - as you have H + ions.

Make sure the overall charge is the same on both sides of the ionic equation.

Double-check your work! Make sure there are equal numbers of each type of atom on both sides of the equation.

Electrons on both sides of the ionic equation must cancel out. Inspect the final equation to make sure it is balanced. It's fine to change coefficients as long as you change them on both sides of the equation. You may need to multiply the electrons by the two half-reactions to get the charge to balance out. Add e - (electrons) to one side of each half-reaction to balance charge.

Repeat this with the other half-reaction.

You want the same number of atoms of each element on each side of the equation.

For one of the half-reactions, balance the atoms except for O and H.

This means identifying and separating the reaction into an oxidation half-reaction and a reduction half-reaction.

Separate the net ionic equation into the two half-reactions.

A table is provided to help you determine whether or not a chemical is soluble, but it's a good idea to memorize the solubility rules. Insoluble compounds do not dissociate into ions, so they are represented by the molecular formula.

The pH of a solution can cause them to dissociate, but in those situations, you'll be presented an ionic equation, not a word problem. Water, weak acids, and weak bases are examples of weak electrolytes. Weak electrolytes yield very few ions in solution, so they are represented by their molecular formula (not written as ions). Examples of strong electrolytes are strong acids, strong bases, and soluble salts. Strong electrolytes dissociate entirely into their ions in water. If you are given a word equation to balance, you'll need to be able to identify strong electrolytes, weak electrolytes, and insoluble compounds. Write the net ionic equation for the unbalanced reaction.

Balanced net ionic equation calculator