Question

why the necessity of partial equation method ?

Answer 1

Partial equation method for balancing a chemical equation:This method is used when a chemical equations contains many reactants and products and it cannot be balanced by hit and trial method.

In this method, the overall reaction is assumed to take place through two or more simpler reactions which can be represented by partial equations. The partial equations are balanced. The intermediate products/reactants are cancelled out while adding the partial equations to give the final balanced equation.


For example:

Zn + HNO3 → Zn(NO3)2+ NH4NO3 + H2O

1) Splitting the complex equation in partial equations:

a) Zn + HNO3 → Zn(NO3)2 + H​

b) HNO3+ H → NH3+ H2O

c) NH3+ HNO3 → NH4NO3

2) Balancing partial equations:In equation a), multiply HNO3by 2 to balance N and O atoms. Then multiplying H by 2 in order to balance hydrogen atoms

​​a) Zn + 2HNO3 → Zn(NO3)2 + 2H

In equation b), first to balance oxygen atoms multiply H2O by 3 then to balance H-atoms multiplying H by 8 on reactants side.

b) HNO3 + 8H → NH3 + 3H2OEquation

c) is balanced.c) NH3 + HNO3 → NH4NO3


Multilying whole equation a) by 4, so that number of H-atoms produced become 8, which then can be cancelled by the 8 H-atoms in equation b) reactants.The final partial equations are:

a) 4Zn + 8HNO3 → 4Zn(NO3)2 + 8H

b) HNO3 + 8H → NH3 + 3H2O

c) NH3 + HNO3 → NH4NO3

Adding the above three equations we get,4Zn + 10HNO3 → 4Zn(NO3)2+ NH4NO3+ 3H2O

Answer 2

HEY MATE ✌✌✌✌✌✌✌

HERE IS YOUR ANSWER :-

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In order to balance simple chemical equations hit and trial method is the best , but for the complex equations this method is not so effective .

since the different elements appear several times in a complex equations , it's balancing takes much times in a complex equations , its balancing takes much time.it is also not clear how the reaction took place.

it is because of these drawback of the hit and trial method that partial equation method is needed to balance such equations.

Partial equation method :- this method is used in balancing complex equations. Here the main reaction is presented in several simple steps . then all the simple reactions are balanced by hit and trial method and added .

then the balancing of equations becomes easy .

✨ Example :- skeleton equation

Cu + HNO3 —> Cu (NO3)2 + H2O + NO

BALANCE EQUATION ,

3Cu + 8HNO3 —> 3 CU (NO3)2 + 2NO + 4H2O

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I HOPE IT MAY HELPFUL FOR YOU ✌✌✌✌✌✌ ✌✌✌✌✌✌✌✌✌✌✌✌✌✌
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