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swati sharma
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X Science and Technology Note on Chemical Reactions, created by swati sharma on 20/02/2018.

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swati sharma
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Chemical Reactions

5/11
Steps to balance equation

Fe + H2O --> Fe3O4 + H2

Step 1: Identify each formula in the equation

            Fe

            H2O

            Fe3O4

            H2 

Step 2:

  1. Identify the elements in the equation
  2. List the number of atoms in LHS and RHS

Fe --> LHS = 1 atom ; RHS =1 atom

H --> LHS = 2 atoms ; RHS =2 atom

O --> LHS =1 atom ; RHS = 4 atoms

no. of atoms differ because of the chemical formula

3Fe needs to combine with 4O to form a stable ferrous oxide molecule

Step 3:

Identify the compound with maximum no. of atoms (can be on any side of the equation)

Fe3O4 

Step 4:

Choose an element in the compound

O

Step 5:

  1. no. of atoms in LHS of O --> 1
  2. no. of atoms in RHS of O --> 4
  3. balance in LHS (as it is less)
  4. to balance 1x4 H2O ( as O is present in that compound)

Equation now becomes 

Fe + 4H2O --> Fe3O4 + 4H2

Step 6: 

Repeat steps 4 and 5 for all elements in the equation

For H

  1. no. of atoms in LHS --> 8 (4x2)
  2. no. of atoms in RHS --> 2
  3. balance RHS ( as it is less)
  4. to balance  1x4 H2 (4x2=8)

        Equation becomes: Fe +4H2O --> Fe3O4 + 4H2

For Fe

  1. no. of atoms in LHS --> 1
  2. no. of atoms in RHS --> 3
  3. balance LHS ( as it is less)
  4. to balance 1x3 Fe

Equation becomes : 3Fe + 4H2O --> Fe3O4 +4H2