Ionic reactions are very common in chemical processes. Ionic reactions involve the binding and dissociation of ions, molecules that have an *electric charge due* to a missing or additional electron.

When ionic compounds interact, the resulting product can be either an ionic or molecular compound. How can this be?

It comes down to what is known as the * net ionic equation* of a reaction. This is how you can determine if a reaction produces only ions or only molecules when two compounds interact.

To learn more about how to determine the net ionic equation of a reaction, read on!

Ionic compounds can be broken down into two categories: cations and anions. Cations are positively charged ions, and anions are negatively charged ions. When these two types of ions interact, there are *three possible outcomes* for the resulting product.

## Find the number of Pb(no3)2 molecules

First, you must find the number of MgSO4 molecules that will be produced when one Pb(NO3)2 molecule is dissolved. One Pb(NO3)2 molecule will produce one MgSO4 molecule and two Pb(NO3)2 molecules.

Next, you must find the number of MgSO4 molecules that will be produced when one Pb(NO3)2 molecule is dissolved. One Pb(NO3)2 moleculedwill produce two MgSO4 molecules and one Na+ ion and two Na+ ions.

Then, you must subtract the second number from the first number to find the total amount of solute formed. There will be a total of two MgSO4 molecules and three Na+ ions after dissolving one Pb(NO3)*2 moleculedin one liter* of solution.

## Find the number of MgSO4 molecules

To determine the number of MgSO4 molecules, you have to find the total number of atoms in the resulting molecule. You can do this by finding the total number of atoms in each molecule that is being added and subtracting that from the total number of atoms in the reacting molecules.

You **would find 1 magnesium ion**, *2 sulfur ions*, and 8 oxygen ions in the resulting molecule. Subtracting those numbers from the total number of atoms in two Pb(NO3)**2 molecules gives** you 0; there are no more atoms in the resulting MgSO4 than there were in the original Pb(NO3)2 molecules.

The net ionic equation is therefore Mg2+ + 2(NO3)– + SO4–2 Mg2+[SO4–2] 2MgSO4.

## Create a table showing the moles for each element

To determine the number of moles of each element in a reaction, you must know the masses of each element and the relative ratios of each element in the reaction.

You can determine the mass ratio of Pb to Mg by weighing a sample of Pb and Mg and calculating the ratio. You can find the number of moles of Pb(NO3)2 by calculating the mass using its molecular weight and dividing by Avogadro’s number (6.02 × 1023).

The first step is to create a table with three columns: one for each element involved in the reaction (Mg, Pb(NO3)2, and SO4−); one for each column containing the relative numbers of atoms or molecules; and one for listing all **possible ionic compounds** that could be formed as a result of this reaction.

The last column is needed because there are two ions in this reaction (Mg2+ and SO4−), so there are more possible products than just magnesite.

## Create an equation showing all elements present

In this case, you would create an equation showing all of the elements that are present in the reaction mixture. You would do this by listing all of the reactants and then adding a row of zeros under the *reactant columns*.

Then, you would add a row of zeros to the left of the Products column and one to its right. These zeros represent all of the products in the solution after the reaction is complete.

This is known as an *ionic equation* and shows all of the compounds that are present after the reaction is complete. All of these compounds are in **neutralized form**, meaning there is an equal number of positively and **negatively charged ions**.

An example of an ionic equation for this scenario would be: Pb(no3)2(s) + 2MgSO4(aq) 2Pb2+ + Mg2+ + SO4-2.

## Balance the equation by adding coefficients

When the reaction is complete, the number of moles of each product is the same as the number of moles of each reactant. The ratio of products to reactants is called the equilibrium constant, Kc.

Ionic equations are balanced using a *method called coefficient substitution*. This process adds a coefficient to each atom or group of atoms in the reaction equation. These coefficients are calculated by adding up all of the charges in the reaction and dividing by two.

Coefficients are then added to both sides of the equation to *make two chemically identical equations* that balance each other. One equation has more molecules on one side, and the other has more coefficients on the other side to make them equivalent.

At the end, all of the coefficients are canceled out and only **quantities remain**.

## Find the numerical value of each coefficient

First, find the total number of moles of each element present in the reaction. To do this, add up the numbers of atoms of each element present in the reaction.

Then divide the number of moles of Pb(NO3)2 by the number of moles of MgSO4. This yields the ratio of ions Pb2+ to Mg2+.

For example, if you have 1 mole Pb(NO3)2 and you have a ratio of 1 mole Mg2+ per 1 mole Pb2+, then you have a neutral reaction (no *net ionic equation*). If you have 1 mole Pb(NO3)2 and you have a ratio of 2 moles Mg2+, then you have a net ionic equation that favors formation of magnesium ions.

## Calculate molar concentrations using concentration units

The concentration unit for moles is mol/L. This means one liter of solution contains one mol of substance. One mole is defined as the amount of a substance that contains six natural numbers of atoms or molecules.

Concentrations can also be expressed in moles per volume, also known as molarity. One mole per liter is one mol/L, for example. One mole per kilogram is onemol/kg, and **one mole per gram** is onemol/g.

To calculate the molar concentrations of the reagents and products in this reaction, you need to know how many moles of each compound are involved in the reaction. You can then use these numbers to calculate the molar concentrations of each reactant and product!

You first need to figure out how many moles of Pb(NO3)2 are needed to *produce one million metric tons* of MnO2. Then, you need to find out how many moles of MnO2 are produced by one million metric tons of MnO2.