What's the balanced chemical equation for N2 + H2 = NH3 ?

Question

I want to know how to balanced equations

Answer 1

Hi Maninoa from Walpahu !

 

   In general before one attempts to balance the masses in a chemical reaction is necessary to determine first if there is a change of oxidation state  (* ) from the reactants to the product of the reaction..If there is a change the total units of oxidation-reduction must be first balanced before balancing the mass.

In this case :   N2 + H2 = NH3   N2 is in the 0 oxidation state ( uncombined) and as a product in NH3

is in the -3 oxidation state ( because it is combined with 3H+) this means  there is a reduction of 3 units per N atom  and a total of 6 for the 2 atoms reacting.. now H is in the 0 oxidation state also and is oxidized to the +1 state in the product NH3 and since there are 2 of them the total oxidation units are2.

  A reaction requires the number of oxidation units to be equal to the reduction units. We can obtain this by using 3 molecules of H . If we use 3H2,the equation will be balanced in redox units.

 

 

              N2+ 3H2  = NH3

 

Now the mass balance.

There are 2 N on the left and only one on the right. a coefficient of 2 for NH3 will satisfy the mass requirements  ( 2N,left; 2N right; 6H left; 6H right )

 

                                    N2 + 3H2  = 2 NH3

 

 

                                  _________________________________

 

(*) the oxidation state of an atom is the number of valence electrons shared or exchanged to produce the chemical bond between to different atoms. Uncombined atoms  or atoms of the same elements combined to form a molecule are considered to be in the 0 oxidation state.

  A few examples for calculating the state of oxidation:

 

          1.  state of oxidation of Cl in   KCl .

Potassium is a metal ( electropositive ) and monovalent .since Cl is combined with one K it most behave as monovalent negative , hence Cl is in the -1 oxidation state

          2.    state of oxidation of Cl in HClO4

Cl is bound to 4O. Since O is electronegative and divalent  (_2} x 4 =-8 and 1H ( 1+ ).

one of the negative valence of oxygen is compensated by one positive valence of H and the remaining 7 negative valences must be compensated by Cl.   In this case then Cl is in the +7 oxidation state.

          3.  State of oxidation of S in  H2SO4.

 

    S is bound to 4O  ( -8 total negative valences ) and 2 H  ( 2 positive valences ) the 6 free negative valences must be compensated by S .In this compound S is in the +6 oxidation state.

 

 

   Kind Regards.

 

Ed 

Answer 2

Balance the equation N₂ + H₂ ⇒ NH₃

• Balancing chemical equations is usually easier than it looks
• There are 2 Nitrogens and 2 Hydrogens on the left side
• There are 1 Nitrogen and 3 Hydrogens on the right side
• Hydrogen seems to be the more complicated term so we should start with that

_N₂ + _H₂ ⇒ _NH₃

• With 2 H on one side and 3 on the other, our common multiple is 6
• To balance the H we need to multiply H₂ by 3 and NH₃ by 2

_N₂ + 3H₂ ⇒ 2NH₃

• Now that we have H balanced, we need to look at N
• There are 2 Nitrogens on both sides of the equation, so in this case it is done

N₂ + 3H₂ ⇒ 2NH₃