Balanced Chemical Equation
Balanced chemical equations
According to law of
conservation of mass that mass can neither be created nor destroyed in a
chemical reaction. It means to say that the total mass of the elements in the
products side of a chemical reaction to
be equal to the total mass of the elements in the reactants side.
Here , the total
number of atoms of each elements remains same before and after a chemical
reaction.
Example :--
Zinc + Sulphuric acid ➡ Zinc sulphate + Hydrogen
Zn + H2SO4 → ZnSO4 +H2
Elements number of atoms in reactants (LHS)
Zn 1
H 2
S 1
O 4
Elements number of atoms in products (RHS)
Zn 1
H 2
S 1
O 4
Balance chemical equation :--
The number of atoms of each elements are
the same on both sides of the arrow is known as balanced chemical
equation.
There are following steps to write the balanced
chemical equation :--
Step1:-- write the given equation to balance the
chemical equation with the help of chemical formulae.
Fe + H2O → Fe3O4 + H2
Step 2:-- write the number of atoms of each elements
present in the unbalanced equation.
We write each side of the
equation. It means that the total number
of atoms present in each elements on the products and reactants side must be
compared.
Fe + H2O → Fe3O4 + H2
Here ,
In left side, the number of
atoms of element in reactants (LHS):--
1 Fe (Iron)
2 H (hydrogen)
1 O (Oxygen)
In Right side, the number of
atoms of element in Products (RHS):--
3 Fe (Iron)
2 H (Hydrogen)
4 O (Oxygen)
Step3:-- to write the balanced chemical equation , the
reactants put on the left hand side
(LHS) and the products are to write on the right hand sided (RHS).
Now, the stoichiometric
coefficients are added to molecules containing an element that has a different
number of atoms in the reactant and products.
Here coefficients mean the number in front of
the chemical formula and coefficient indicates the mole of the compound. And
subscripts mean the number below the atom that indicates the number of atom in
a single molecule.
Here, the coefficient must
balance the numbers of atoms on each side.
to calculate the number of
atoms , multiply the coefficient and subscripts. And the number of atoms of the
elements on both the reactants and products side must be added and updated.
To balance the above equation
, let us start with the compound with msximum number of atoms , we select Fe3O4 . and
in this compound the maximum number of the atoms are oxygen. Here , there are four oxygen
atoms on the RHS and only one atoms on LHS.
To balance the oxygen atoms:--
Atoms of oxygen in reactant in
products
Initial 1 (in H2O) 4(in Fe3O4)
To balance 1*4 4
To equalise the number of
atoms , it must be noted that we cannot alter the formulae of the compounds or
elements involved in the chemical reactions. For example :-- to balance the
oxygen atoms , we can put coefficient “4” as 4H2O and not H2O4
or (H2O)4.
The partly balanced equation
becomes :--
Fe +
4H2O → Fe3O4
+ H2 (partly balanced)
Step4:--
Step 3 is repeated until the
number of atoms on both side reactants and products becomes equal. Let us
balance the hydrogen atoms in the partly balanced equation.
To equalise the number of
hydrogen H atoms , make the number of molecules of hydrogen as four on the RHS.
Atoms of hydrogen in
reactants in products
Initial 8 (in 4 H2O) 2(in H2)
To balance 8
2*4
The equation will be :--
Fe + 4
* H2O → Fe3O4 +
4H2 (this is partly balanced
equation)
Step5:--
Now the above equation is found partly
balanced, we find the only one element is left to be balanced that is IRON (Fe)
Atoms of iron Fe in
reactants in products
Initial 1 (in Fe) 3 (in Fe3O4)
To balance 1*3 3
The equation will be :--
3
Fe + 4 H2O → Fe3O4
+ 4H2
Step 6:-- now
we check the correctness of the balanced equation. Count the atom of each
elements on both side of the equation.
3 Fe +4
H2O → Fe3O4 + 4H2 (balanced equation)
The number of atoms are
equal on both sides. This equation is balanced equation. This method of
balancing chemical equations is called as hit and trial method as we make
trials to balance the equation by using the smallest whole number coefficient.
Step
7:-- writing symbols
of physical state.
The physical states of the reactants and
products are mentioned along with their chemical formulae. This makes the
balanced equation is more effective and informative. The phases of the
reactants and products are mentioned using the symbols are such as
Gaseous ---- g
Liquid ----- l
Solid ----------- s
Aqueous ---- aq
Noted that the aqueous
(aq) is written if the reactants or products is present as solution in water.
The balanced equation
is represented as :--
3 Fe + 4 H2O (g) → Fe3O4 (s)
+
4H2(g) (balanced
equation)
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