How to Write the Net Ionic Equation for NaOH + MgCl2 = NaCl + Mg(OH)2

There are three main steps for writing the net ionic equation for NaOH + MgCl2 = NaCl + Mg(OH)2 (Sodium hydroxide + Magnesium chloride). First, we balance the molecular equation.

Second, we write the states and break the soluble ionic compounds into their ions (these are the strong electrolytes with an (aq) after them). Finally, we cross out any spectator ions. These are the ions that appear on both sides of the ionic equation.

If you are unsure if a precipitate will be present when writing net ionic equations, you should consult a solubility table for the compound. Another option to determine if a precipitate forms is to have memorized the solubility rules. In this reaction, Mg(OH)2 will be slightly soluble and is considered a precipitate (solid) and will fall to the bottom of the test tube. We consider this to be insoluble in net ionic equations. Because of this Mg(OH)2 will be a precipitate and therefore write the state symbol (s) after the compound that precipitates out of solution.

If you are unsure if a compound is soluble when writing net ionic equations you should consult a solubility table for the compound.

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Important Skills

Finding Ionic Charge for Elements: youtu.be/M22YQ1hHhEY
Memorizing Polyatomic Ions: youtu.be/vepxhM_bZqk
Determining Solubility: youtube.com/watch?v=5vZE9K9VaJI


More Practice

Introduction to Net Ionic Equations: youtu.be/PXRH_IrN11Y
Net Ionic Equations Practice: youtu.be/hDsaJ2xI59w
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General Steps:

1. Write the balanced molecular equation.
2. Write the state (s, l, g, aq) for each substance.
3. Split soluble compounds into ions (the complete ionic equation).
4. Cross out the spectator ions on both sides of complete ionic equation.
5. Write the remaining substances as the net ionic equation.


Writing and balancing net ionic equations is an important skill in chemistry and is essential for understanding solubility, electrochemistry, and focusing on the substances and ions involved in the chemical reaction and ignoring those that don’t (the spectator ions).

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