How to balance chemical reaction ?

Befor balancing equations we learn about chemical reaction, what is chemical reaction? And we learn what is balanced equation and unbalanced equation. So let's start... 

Introduction :-

• Chemical reaction 
• Balanced equation and unbalanced equation 
• How to equal chemical reaction 

Home page 

Read in hindi click here

Chemical reaction :-

                              The phenomenon of chemical change (change in chemical composition and chemical properties of a substance) in a substance is called chemical reaction.

Example  -

    Mg  +  O2   MgO

Balanced equation and unbalanced equation :-

Count the number of atoms of the elements to the left and right of the arrows and compare them. Do the elements on both sides have the same number of atoms? If so, then the equation is balanced. If not, then the equation is unbalanced because the masses on both sides of the equation are not equal. Such a chemical equation structure of a reaction is called a chemical equation. Thus, equation  T is the structure equation for the burning of magnesium in air.

Now let us try to balance the following chemical equation:

Fe  + H2O ➡  Fe3O4+ H2

(14)

Step 1: 

              To balance the chemical equation, first draw a box around each formula. Do not change anything inside the box while balancing the equation.

(Fe)  + (H2O) ➡ (Fe3O4)+ (H2)

 (15)

Step 2: 

                    Match the atoms of different elements present in the unbalanced equation (1.5) Make a list of numbers.

Element       Number of Atoms in.        atoms in products

Number        the Heads (LHS)                  Number of (RHS)

Fe                                      1                                       3

H                                      2                                        2  

O                                     1                                        4

Step 3: 

               For convenience, first balance the compound with the largest number of atoms whether it is reactant or product. Select the element with the highest number of atoms in that compound. On this basis we choose Fe, O, and its oxygen element. There are four oxygen atoms on the right side while only one on the left. To balance the oxygen atom:

oxygen atoms    in the reactants     in products

(i) in the beginning     1 (in HO)         4 (FeO, in) 4

(ii) To balance           1x4=4                       4

It is important to remember that in order to equalize the number of atoms, we cannot change the formulas of the elements and compounds involved in the reaction. As ifTo balance the oxygen atom, we can write 4 H2O by applying the coefficient '4' but not HO, or (H, O). 

The partially balanced equation will now be as follows:

(Fe) + 4(H2O) ➡ (Fe3O4)+ (H2)

(1,6)

                                                (partially balanced equation)

Step 4: 

                      Fe and H atoms are still not balanced. We proceed by choosing one of these elements. Now we balance the hydrogen atom in the partially balanced equation:

To equalize the hydrogen atom, the number of hydrogen molecule on the right Let's do '4'. 

Hydrogen atomsin.      in the reactants.      in products

(1) in the beginning       8 (in 4H2O)              2(in H2)

(II) To balance.                 8                            2x4=8

The equation will now be as follows:

(Fe) + (H2O) ➡ (Fe3O4)+ (H2)

                                      (Partly Balanced Equation) 

Step 5:  

                Check the above equation and select the third element which is still unbalanced. You will find that iron is the only element that has to be balanced.

   iron atoms           in the reactants           in products

(i) in the beginning.       1( in Fe)              3(Fe3O4)

(ii) to balance.                   1x3                      3

To balance Fe, we take 3 atoms of Fe on the left.

 3 (Fe) + 4 (H2O)  ➡  (Fe3O4)+4 (H2)

(1.8)

Step 6:

                Finally, to check this balanced equation, we calculate the number of atoms of the elements on both sides of the equation.

3 Fe+ 4H2O  ➡  Fe304 +4H2

(1.9)

(Balanced Equations) In Equation (1.9), the number of atoms of the elements on both sides are equal. So this equation is now balanced. This method of balancing chemical equations is called the hit and trial method because we try to balance the equation by using the coefficient of the smallest integer number.

Step 7: 

                Writing the Signals of the Physical States: Examine the balanced equation (1.9) given above carefully. Does this equation also give us knowledge about the physical states of the reactants and products? There is no information about their physical states in this equation.

To make the chemical equation more informative, the chemical formulas of the reactants and products are shown along with their physical states. The gas, liquid, aqueous and solid states of the reactants and products, respectively (g). It is denoted by (l), (aq) and (s). When the reactants or products are present in the form of solution in water, we write (aq).

3Fe(s) + 4H2O(g) ➡ Fe3O4(s)+ 4H2(g)

(1.10)

Note that in Eq. (1.10) the sign (g) is used with HO. This shows that water is used in the form of steam in this reaction. Physical states are not included in almost every chemical equation.