Balance by partial methods

P4 + hno3 = h3po4+ no2+h2o

P4 + 16H2O ==> 4H3PO4 + 20e + 20H^+

1H^+ + 1e + HNO3 ==> NO2 + H2O

Multiply to keep the electrons equal and add the equations together. Finally, cancel ions/molecules common to both sides.

Its wrong

P4 + HNO3 ---------> H3PO4 + NO +H2O

-> P4 + H2O -> H3PO4
Then using hit and trial method
P4 + H2O -> 4H3PO4 + 10[O]
(addition of 10 atoms of oxygen i.e. nascent oxygen to make the equation balanced)
-> HNO3 -> NO2 + H2O
Again using hit and trial method
2HNO3 +[O] -> 2NO2 + H2O
(addition of 1 atom of nascent oxygen to make the equation balanced)
NOTE : THE SAME EXTRA ATOM HAS TO BE MULTIPLIED ON BOTH THE SIDES AS PER THE SITUATION AND MUST BE CUT AT LAST
Now adding both the equations to make a single balanced equation
P4 + H2O -> 4H3PO4 + 10[O]
+ 2HNO3 +[O] -> 2NO2 + H2O } ×10
————————————————————
P4 + 20HNO3 -> 4H3PO4 + 2NO + 9H2O
AT last the oxygens and 1 water molecule get cancelled and the above answer remains
Hence done......=)

To balance the chemical equation P4 + HNO3 = H3PO4 + NO2 + H2O, you need to follow a step-by-step process. Here's how you can do it:

Step 1: Count the atoms on both sides of the equation.

On the left side of the equation, you have 1 P atom, 4 H atoms, 1 N atom, and 3 O atoms.
On the right side of the equation, you have 1 P atom, 4 H atoms, 1 N atom, and 5 O atoms.

Step 2: Begin balancing the equation by adjusting the coefficients of the compounds.

Let's start by balancing the phosphorus (P) atoms. Since there is only one P atom on each side of the equation, the coefficients for P4 on the left side and H3PO4 on the right side should be the same.

P4 + HNO3 = H3PO4 + NO2 + H2O

Next, let's balance the nitrogen (N) atoms. On the left side, there is one N atom in HNO3, so the coefficient of NO2 should be 1.

P4 + HNO3 = H3PO4 + NO2 + H2O

Now let's balance the hydrogen (H) atoms. There are 4 H atoms on both sides of the equation, so they are already balanced.

P4 + HNO3 = H3PO4 + NO2 + H2O

Finally, balance the oxygen (O) atoms. On the left side, there are 3 O atoms in HNO3, so the coefficient for H3PO4 on the right side should be 3.

P4 + HNO3 = 3H3PO4 + NO2 + H2O

Step 3: Check that all the atoms are balanced.

Count the atoms again to verify that they are now balanced:

On the left side: 4 P atoms, 1 N atom, 3 O atoms, and 1 H atom
On the right side: 4 P atoms, 1 N atom, 3 O atoms, and 4 H atoms

Since both sides of the equation now have the same number of each atom, the equation is balanced:

P4 + HNO3 = 3H3PO4 + NO2 + H2O