help balance this redox equation:
HNO3 + Zn(s) <==> NO(s) + ZnO
...i know i need H2O and possibly H+
Where did you get this reaction. I don't buy into ZnO. More likely Zn(NO3)2.
its from our che 302 hw...
the answer choices are:
1. 2 HNO3 + 3 Zn(s) <==> 2 NO(s) + 3 ZnO + H2O
2. 2 HNO3 + 3 Zn(s) <==> 2 NO(s) + 3 ZnO
3. HNO3 + Zn(s) + H+ <==> NO(s) + ZnO + H2O
4. 3 HNO3 + 2 Zn(s) <==> 3 NO(s) + 2 ZnO
5. 3 HNO3 + 2 Zn(s) + 7 H+ <==> 3 NO(s) + 2 ZnO + 5 H2O
And what is your problem in doing it yourself? That is, what do you not understand?
im thinking its either 1 or 3 but im not sure if i need to add in H+ or not..
Again, what do you not understand about it? You don't want to guess, you want to KNOW you are right.
Here is a hint:
For a redox equation to be balanced, it must contain two things:
1. Atoms must balance.
2. Transfer of electrons must balance.
So count the atoms on both sides and count the exchange of electrons.
You didn't type all of the question, I suppose, but from what you posted it doesn't ask what must be added. It asks which of the choices is correct.
To balance a redox equation, follow these steps:
Step 1: Separate the equation into half-reactions. In this case, one half-reaction involves the oxidation of Zn(s) to ZnO, and the other half-reaction involves the reduction of HNO3 to NO.
Zn(s) -> ZnO (oxidation)
HNO3 -> NO (reduction)
Step 2: Balance the atoms other than hydrogen and oxygen. Start by balancing the atoms that appear in fewer species. In this case, Zn and N are good candidates.
Balancing the zinc (Zn) atoms:
Since there is only one Zn atom on both sides, they are already balanced.
Balancing the nitrogen (N) atoms:
There are two nitrogen atoms on the left side due to HNO3 and only one on the right side due to NO. To balance the nitrogen atoms, add a coefficient of 2 in front of NO to have 2NO.
Zn(s) -> ZnO (oxidation)
HNO3 -> 2NO (reduction)
Step 3: Balance the charges. In a redox reaction, the total charge must be the same on both sides.
Balancing the charges:
On the left side, the Zn(s) atom has a charge of 0, while on the right side, ZnO has a charge of +2. Since Zn gains two electrons, add a coefficient of 2 in front of ZnO.
2Zn(s) -> ZnO (oxidation)
HNO3 -> 2NO (reduction)
Step 4: Balance the oxygen atoms by adding water molecules (H2O) to the side that needs more oxygen. In this case, the left side needs more oxygen.
Balancing the oxygen atoms:
On the left side, there are no oxygen atoms, while on the right side, there are two oxygen atoms present in ZnO. To balance it, add a coefficient of 2 in front of HNO3 and a coefficient of 2 in front of H2O.
2Zn(s) -> ZnO (oxidation)
2HNO3 -> 2NO + H2O (reduction)
Step 5: Balance the hydrogen atoms by adding protons (H+) to balance the charges and hydroxide ions (OH-) to balance the hydrogen atoms.
Balancing the hydrogen atoms:
On the left side, there are no hydrogen atoms, while on the right side, there are two hydrogen atoms in H2O. To balance it, add 4H+ to the left side.
2Zn(s) + 4H+ -> ZnO (oxidation)
2HNO3 -> 2NO + H2O (reduction)
Step 6: Balance the charges again.
Balancing the charges:
On the left side, Zn has a charge of 0, while on the right side, ZnO has a charge of +2. To balance it, add 2 electrons (2e-) to the left side.
2Zn(s) + 4H+ + 2e- -> ZnO (oxidation)
2HNO3 -> 2NO + H2O (reduction)
Now, the redox equation is balanced, and the final balanced equation is:
2HNO3 + Zn(s) + 2H+ -> 2NO + ZnO + H2O