Chemical equations:
To understand chemical reactions more clearly and represent them precisely and scientifically, scientists use chemical equations. A chemical equation is the symbolic representation of a chemical reaction using chemical formulae.
Writing a chemical equation:
- Reactants: LHS
- Products: RHS
- Right arrow (→): Direction reaction by pointing to the products
- Physical states: Solid – (s), Liquid – (l), Gas – (g), Aqueous – (aq)
Law of conservation of mass:
According to the law of conservation of mass, mass can neither be created nor destroyed in a chemical reaction.
Therefore, the number of atoms of each element must be the same on both sides of a chemical equation.
Therefore, the number of atoms of each element must be the same on both sides of a chemical equation.
Word equation:
Iron + Water → Iron oxide + hydrogen
Skeletal chemical equation:
\(Fe + H_2O → Fe_3O_4 + H_2\)
This equation is unbalanced because the number of atoms on both sides is not equal.
Balancing chemical equations (Hit and trial method):
This method involves adjusting coefficients to ensure that atoms are balanced on both sides using the smallest whole numbers.
\(Fe + H_2O → Fe_3O_4 + H_2\)
Steps to balance:
- Count the atoms of each element on both sides .
| Element |
Number of atoms in reactants (LHS)
|
Number of atoms in products (RHS)
|
|
\(Fe\)
|
\(1\)
|
\(3\)
|
|
\(H\)
|
\(2\)
|
\(2\)
|
|
\(O\)
|
\(1\)
|
\(4\)
|
- Add coefficients to balance
- Check for correctness
- Include physical states
Balanced equation:
\(3Fe({s}) + 4H_2O({g}) → Fe_3O_4({s}) + 4H_2({g})\)
Reaction conditions like temperature, pressure, or catalysts may be written above or below the arrow.