Question

The variable coefficients a, b, c and d are considered for balancing the chemical equation. Relationships between these variable are constructed by balancing the atoms of each element on either side of the reaction. Which of the following are correct?

(Note: coefficients should be natural numbers)

• A. a = 2b = 2c = d and a+b = c+d
• B. 2a = b = c = 2 d and a+c = b+d
• C. a = b = 2c = 2d and 2a+3b = c + 2d
• D. None of the above

Answer 1

The correct option is A

a = 2b = 2c = d and a+b = c+d

Select element Potassium (K), there are 'a' number of atoms of it on reactant side and '2c' number of electrons on product side and these should be equal.

=>$a=2c$

similarly, doing this for other elements, we get,

$$\begin{array}{cccc}Element& Numberofatomsonreactantside& Numberofelementsonproductside& Equationformed\\ Potassium& a& 2c& a=2c\\ Nitrogen& a& 2c& a=2c\\ Oxygen& 3a+3b& 3c+3d& a+b=c+d\\ Carbon& b& c& b=c\\ Hydrogen& 2b& d& 2b=d\end{array}$$

So we get the equation(from the table),

$a=2c=2b=danda+b=c+d$

$letb=1$

solving this,

$c=1$

$a=2$

$d=2$

=> balanced equation is

This method can be used to balance equations easily than trial and error.