For the following reaction in acidic solution.
Cr2O7^2- + I- ---> Cr^3+ + IO3-
Give the total balanced net ionic equation.
Break down the equation into reduction and oxidation half equation.
oxidation reaction is
I- --> IO3-
balance the equation starting with oxygen by adding water, then followed by addition of H+ ions to balance H atoms, and then finally the electrons to balance the charges.
You will get something like (for the oxidation);
3H2O + I- --> IO3- + 6H+ + 6e- [6 electrons cancels out the 6+ from H+ leaving a 1- charge from IO3-. This is balanced from the 1- charge by I-]
Do the same with the reduction equation;
Cr2O7^2- --> Cr^3+
when you get both equations balance, cancel out the electrons (you need to manipulate the equation by multiplying each with an integer so that both equations have the same number of electrons). Then add the equations together.
Cr2O7^-2 + I- + 8H^------->2Cr^3+ + IO3^- + 4 H2O
To write the balanced net ionic equation for the given reaction in acidic solution, you need to follow these steps:
Step 1: Write the balanced molecular equation for the reaction.
Cr2O7^2- + 6I- + 14H+ → 2Cr^3+ + 3IO3- + 7H2O
Step 2: Identify the spectator ions. These are the ions that do not participate in the reaction and are present on both sides of the equation. In this case, the H+ ions are spectator ions.
Step 3: Write the net ionic equation by eliminating the spectator ions.
Cr2O7^2- + 6I- → 2Cr^3+ + 3IO3-
Therefore, the total balanced net ionic equation for the given reaction is:
Cr2O7^2- + 6I- → 2Cr^3+ + 3IO3-
To write the total balanced net ionic equation, we need to first write the balanced molecular equation and then separate it into ions to find the net ionic equation. Here's how you can do it:
Step 1: Write the balanced molecular equation:
Cr2O7^2- + 6I- + 14H+ → 2Cr^3+ + 3I2 + 7H2O
Step 2: Separate the equation into ions:
The Cr2O7^2- and the Cr^3+ ions do not dissociate, as they remain as complex ions. The I- ions react to form the I2 molecule, while the H+ ions react with H2O to form H2 gas and dissolve into the solution. So, the balanced net ionic equation is:
6I- + 14H+ → 3I2 + 7H2O
Therefore, the total balanced net ionic equation is 6I- + 14H+ → 3I2 + 7H2O.