steps to balance ionic reactions with examples

steps to balance ionic reactions with examples


2 Answers

askIITians Faculty 652 Points
8 years ago
You can refer to the following rules..
First, write thenet ionic equationfor the unbalanced reaction. If you are givena word equationto balance, you'll need to be able to identify strong electrolytes, weak electrolytes and insoluble compounds. Strong electrolytes completely dissociate into their ions in water. Examples ofstrong electrolytesarestrong acids,strong bases, and soluble salts. Weak electrolytes yield very few ions in solution, so they are represented by their molecular formula (not written as ions). Water,weak acids, andweak basesare examples ofweak electrolytes. The pH of a solution can cause them to dissociate, but in those situations, you'll be presented an ionic equation, nota word problem. Insoluble compounds do not dissociate into ions, so they are represented by themolecular formula. A table is provided to help you determine whether or not a chemical is soluble, but it's a good idea to memorize thesolubility rules.
Separate the net ionic equation into the two half-reactions. This means identifying and separating the reaction into an oxidation half-reaction anda reduction half-reaction.
For one of the half-reactions, balance the atoms except for O and H. You want the same number of atoms of each element on each side of the equation
Repeat this with the other half-reaction.
Add H2O to balancethe O atoms. Add H+to balancethe H atoms. The atoms (mass) should balance out now.

Now balance charge. Add e-(electrons) to one side of each half-reaction tobalance charge. You may need to multiply the electrons thethe two half-reactionsto get the charge to balance out. It's fine to change coefficients as long as you change them on both sides of the equation.

Now, add the two half-reactions together. Inspect the final equation to make sure it is balanced. Electrons on both sides of the ionic equation must cancel out.

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

Hope this helps you out.
askIITians Faculty 1246 Points
8 years ago
Writing the ionic equation for the word equation

Sodium(s) + hydrochloric acid(aq) -> sodium chloride(aq) + hydrogen(g)


Step 1:Write the equation and balance it.

2Na(s) + 2HCl(aq) -> 2NaCl(aq) + H2(g)

Step 2:Split the ions. (Only compounds that are aqueous are split into ions.)

2Na(s) + 2H+(aq) + 2Cl-(aq) → 2Na+(aq) + 2Cl-(aq) + H2(g)

Step 3:Cancel out spectator ions. (Spectator ions are ions that remain the same in their original states before and after a chemical reaction.)

Step 4:Write a balanced ionic equation

2Na(s) + 2H+(aq) → 2Na+(aq) + H2(g)

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