Balancing a Redox Equation in Acidic Solution

[pompey]

Homework Statement

Balance the following redox equation (in an acidic solution):

Cu + NO₃^- -> NO₂ + Cu²

The Attempt at a Solution

I got 4H⁺ + 2NO₃^- + Cu -> Cu⁺²+ + 2NO₂ + 2H₂O

But my book told me the same thing, but without the H<sup>2[/sub]O:

4H+ + 2NO₃- + Cu -> Cu+2+ + 2NO₂</sup>

 

[symbolipoint]

Your answer is better because YOURS is balanced. The book's answer, by dropping the water from the right-side is not balanced. Check the number of oxygens on the two sides!

 

[Blueshift5]

it is important to understand the principles of redox reactions and how to balance them in different solutions, including acidic solutions. In this particular case, the reaction involves the transfer of electrons from copper (Cu) to nitrate ions (NO3-), resulting in the formation of nitrite ions (NO2) and copper ions (Cu2+). In order to balance this equation in an acidic solution, we must take into account the presence of hydrogen ions (H+) and water (H2O).

Based on the given equation, we can see that there are already two copper atoms on both sides, so we do not need to add any coefficients to balance them. However, there are four hydrogen ions on the right side and none on the left, so we need to add four hydrogen ions to the left side to balance the equation. This is represented by the first term in both solutions provided, 4H+.

Next, we need to balance the nitrate and nitrite ions. In the given equation, there are two nitrate ions on the left side and two nitrite ions on the right side, so we do not need to add any coefficients to balance them. However, we need to account for the overall charge of the ions. On the left side, the copper ion has a charge of 0, while on the right side, the copper ion has a charge of +2. To balance this, we add two electrons (e-) to the left side, as represented by the Cu+2+ term in both solutions.

Finally, we need to balance the oxygen atoms. On the left side, there are six oxygen atoms (from two nitrate ions) and on the right side, there are four oxygen atoms (from two nitrite ions). To balance this, we add two water molecules (H2O) to the right side, as represented by the H2O term in the first solution.

In summary, both solutions provided are correct and equivalent, as they both follow the principles of balancing redox reactions in acidic solutions. The first solution includes the water molecules to explicitly show the balance of oxygen atoms, while the second solution assumes that the reader understands this concept and does not include the water molecules. it is important to be able to understand and interpret both versions of the equation.