Balance the following redox equation by the oxidation number methode
Ag + HNO3 = AgNO3 + NO + H2O
I have all the oxidation numbers i just don't understand how i'm supposed to balance it according to them.
I read the sites and i can't get it.
Do i balance out each side to the same amount of oxidation numbers??
Draw a line, something like this, at the bottom of the equation connecting Ag and AgNO3.
|_______________|. Write zero under Ag and +1 under Ag of AgNO3.
Now draw another line upside down from the one above and place it above the equation connecting N of HNO3 and N of NO2. |--------------| N for HNO3 is +5 and N of NO is +2. Write those in similar to the way you did the Ag and AgNO3.That gives you everything you need to balance it. On the Ag to AgNO3, write
|____loss of 1e______|
On the N to N write
|-----gain of 3e ----|.
You must keep the electrons equal; therefore, multiply the Ag to AgNO3 by 3 and the HNO3 to NO by 1. That gives you the following
3Ag + HNO3 ==> 3AgNO3 + NO + H2O
I'm sure you have all of this already, probably a dozen or more times. The next part is the tricky part.
The redox part is balanced. Now you must recognize that the NO3 in AgNO3 is not reduced like the NO3^- to NO. So we need 1 HNO3 for the NO part of the equation(the redox part) and we need another 3 HNO3 to take care of the 3AgNO3 (from the non-redox part). So 3+1 = 4 and we make it 4HNO3 like this.
3Ag + 4HNO3 ==> 3AgNO3 + NO + H2O.
All you need to do now is to balance the H2O (it's 2H2O) and you'll have it. :-)
OMG Doctor Bob you are a huge help!
And you right i did have that a dozen times lol but i wasn't sure if i had it right because i couldn't het the last part to work out for me!
But i have it now so thanks a bunch!
To balance a redox equation using the oxidation number method, follow these steps:
Step 1: Assign oxidation numbers to all the elements in the equation.
Ag + HNO3 = AgNO3 + NO + H2O
In this equation, the oxidation number of Ag is 0 (because it is an element), the oxidation number of H in HNO3 is +1, the oxidation number of N in HNO3 is +5, the oxidation number of O in HNO3 is -2, the oxidation number of Ag in AgNO3 is +1, the oxidation number of N in AgNO3 is +5, the oxidation number of O in AgNO3 is -2, the oxidation number of N in NO is +2, and the oxidation number of O in H2O is -2.
Step 2: Identify the elements undergoing oxidation and reduction.
In this equation, Ag is undergoing oxidation as its oxidation number is going from 0 to +1, whereas N is undergoing reduction as its oxidation number is going from +5 to +2.
Step 3: Balance the atoms in the equation (excluding H and O) other than the ones undergoing oxidation and reduction.
In this equation, there is only one atom of Ag on each side, so it is already balanced. There is one atom of N on the left side and one atom of N on the right side, so they are already balanced. There are three oxygen atoms on the left side (in the HNO3) and five oxygen atoms on the right side (in the AgNO3 and H2O).
Step 4: Balance the oxygen atoms by adding water (H2O) to the side that needs more oxygen.
Since there are three oxygen atoms on the left side and five oxygen atoms on the right side, we need to add two water molecules (H2O) to the left side to balance the oxygen atoms.
Ag + HNO3 = AgNO3 + NO + 2H2O
Step 5: Balance the hydrogen atoms by adding hydrogen ions (H+) to the side that needs more hydrogen.
Since there are no hydrogen atoms on the right side, we need to add six hydrogen ions (H+) to the right side to balance the hydrogen atoms.
Ag + HNO3 = AgNO3 + NO + 2H2O + 6H+
Step 6: Balance the charge on both sides by adding electrons (e-) to the side that needs more negative charge.
Since the left side is neutral and the right side has a net charge of +6 (from the six hydrogen ions), we need to add six electrons (e-) to the left side to balance the charges.
Ag + HNO3 + 6e- = AgNO3 + NO + 2H2O + 6H+
Step 7: Make the number of electrons gained equal to the number of electrons lost by multiplying the oxidation number of the element undergoing oxidation by the coefficient in front of it and the number of electrons gained by the element undergoing reduction by the coefficient in front of it.
Since Ag is undergoing oxidation, its coefficient is 1, and since N is undergoing reduction, its coefficient is 5.
5e- = 1e-
Step 8: Multiply the half-reactions by appropriate coefficients so that the number of electrons lost and gained are equal.
Multiply the oxidation half-reaction by 5 and the reduction half-reaction by 1:
5Ag + 5HNO3 + 30e- = 5AgNO3 + 5NO + 10H2O + 30H+
Combine the two half-reactions and cancel out any common species on both sides:
5Ag + 5HNO3 + 30e- = 5AgNO3 + 5NO + 10H2O + 30H+
→
5Ag + 5HNO3 + 30H+ = 5AgNO3 + 5NO + 10H2O
Now the equation is balanced following the oxidation number method.
Balancing a redox equation using the oxidation number method involves assigning oxidation numbers to each element in the equation, determining which elements are oxidized and reduced, and then balancing the equation based on the change in oxidation numbers.
Here's how to balance the given redox equation Ag + HNO3 = AgNO3 + NO + H2O:
1. Assign oxidation numbers to each element:
- Ag has an oxidation number of 0 since it is a pure element.
- H has an oxidation number of +1.
- N in HNO3 has an oxidation number of +5 (since oxygen is generally assigned -2).
- O in HNO3 has an oxidation number of -2.
- Ag in AgNO3 has an oxidation number of +1.
- N in AgNO3 has an oxidation number of +5.
- O in AgNO3 has an oxidation number of -2.
- N in NO has an oxidation number of +2.
- O in NO has an oxidation number of -2.
- H in H2O has an oxidation number of +1.
- O in H2O has an oxidation number of -2.
2. Identify the elements being oxidized and reduced:
In this equation, silver (Ag) is being oxidized from an oxidation number of 0 to +1, and nitrogen (N) in nitrate (HNO3) is being reduced from +5 to +2.
3. Determine the change in oxidation numbers:
The oxidation number of Ag increases by +1, while the oxidation number of N decreases by -3.
4. Balance the equation based on the change in oxidation numbers:
To balance the change in oxidation numbers, you need to multiply the species in the equation by appropriate coefficients.
The balanced equation is:
3Ag + 4HNO3 = 3AgNO3 + 2NO + 2H2O
By balancing the equation according to the change in oxidation numbers and the conservation of mass, we ensure that both sides of the equation have the same total charge and number of atoms, thus satisfying the law of conservation of mass and charge.