0Chemical reactions and equations :
Equation:
- Reactant + product = chemical equation
- Reactant; The substance which undergo a chemical change in the reaction
Method of writing a reaction:
- Arrow must be placed between the reactants on Left hand side and product on the right hand side
- Plus sign (+) must be written between the reactants
- Arrow head must point towards the products which shows the direction of the reaction.
Example: Magnesium + oxygen= magnesium oxide
Mg+02→MgO
Balancing. a chemical equation :
- First draw boxes around each formula
- List the number of atoms of different elements present in unbalanced equation
- Start balancing with compound that contains maximum no of atoms
- Finally check the correctness of the balanced equation.
- Write symbols of physical state
Example: step -1
Fe+H20 →Fe3O4+ H2
Step -2 :
| Element | no of atoms in reactants (LHS) | Number of atoms in product (RHS) |
| Fe | 1 | 3 |
| H | 2 | 2 |
| O | 1 | 4 |
step 3:
3Fe+ 4H2O→Fe3O4+4H2
Step 4:
| Element | LHS | RHS |
| Fe | 3 | 3 |
| H | 8 | 8 |
| O | 4 | 4 |
Step 5:
3Fe(s) +4H20(g)→Fe3O4(s) + 4H2(g)
