How to calculate formal charges of sulfuric acid (H2SO4) with lewis structure?
In covalently bonded molecules, formal charge is the charge assigned to an atom based on the assumption that the bonded electrons are equally shared between concerning atoms, regardless of their electronegativity.
The overall formal charge present on a molecule is a measure of its stability.
The fewer the formal charges present on the bonded atoms in a molecule (close to zero), the greater the stability of its Lewis structure.
In this article, we will calculate the formal charges present on the bonded atoms in the king of chemicals, i.e., sulfuric acid (H_{2}SO_{4}), and its overall charge.
So, continue reading!
Name of the molecule | Sulfuric acid |
Chemical formula | H_{2}SO_{4} |
The formal charge on the sulfur (S) atom | 0 |
The formal charge on each S=O bonded oxygen (O) atom | 0 |
The formal charge on each S-O-H bonded oxygen (O) atom | 0 |
The formal charge on each hydrogen (H) atom | 0 |
The overall formal charge on H_{2}SO_{4} | 0 |
How to calculate the formal charges on H_{2}SO_{4} atoms?
The formal charges can be calculated using the formula given below:
The formal charge of an atom = [valence electrons of an atom – non-bonding electrons – ½ (bonding electrons)]
- The valence electrons (V.E) of an atom are the total number of electrons present in its valence shell. Valence electrons can be calculated by locating the position of the elemental atom in the Periodic Table.
- Non-bonding electrons (N.E) are the number of lone pairs present on the atom. (1 lone pair means 2 nonbonding electrons).
- Bonding electrons (B.E) are the total electrons shared with the atom via covalent chemical bonds. (1 single bond means 2 bonding electrons).
The most preferred Lewis representation of sulfuric acid (H_{2}SO_{4}) is as shown below.
It consists of a total of 32 valence electrons. A Sulfur S-atom is present at the center. It is double-bonded to two oxygen (O) atoms and single-bonded to two hydroxyls (OH) functional groups.
No lone pair of electrons is present at the central S-atom or at any of the two H-atoms. Contrarily, each oxygen atom carries two lone pairs of electrons in the above Lewis structure.
It is the best possible Lewis structure of H_{2}SO_{4} because the formal charges are minimized in it, and thus, it is also the most stable.
Now let’s find the formal charges present on each atom in the most stable H_{2}SO_{4} Lewis structure by applying the formal charge formula given above.
For the sulfur atom
- Valence electrons of Sulfur = It is present in Group VI A = 6 valence electrons
- Bonding electrons = 2 single bonds + 2 double bonds = 2(2) + 2(4) = 12 electrons
- Non-bonding electrons = no lone pair = 0 electrons
- Formal charge = 6 – 0 – 12/2 = 6 – 0 – 6 = 6 – 6 = 0
∴ The formal charge on the central sulfur (S) atom in H_{2}SO_{4} is 0.
For each S=O bonded oxygen atom
- Valence electrons of oxygen = It is present in Group VI A = 6 valence electrons
- Bonding electrons = 1 double bond = 4 electrons
- Non-bonding electrons = 2 lone pairs = 2(2) = 4 electrons
- Formal charge = 6 – 4 – 4/2 = 6 – 4 – 2 = 6 – 6 = 0
∴ The formal charge on each S=O double-bonded oxygen (O) atom in H_{2}SO_{4} is 0.
For each S-O-H bonded oxygen atom
- Valence electrons of oxygen = It is present in Group VI A = 6 valence electrons
- Bonding electrons = 2 single bonds = 2 + 2 = 4 electrons
- Non-bonding electrons = 2 lone pairs = 2(2) = 4 electrons
- Formal charge = 6 – 4 – 4/2 = 6 – 4 – 2 = 6 – 6 = 0
∴ The formal charge on each S-O-H bonded oxygen (O) atom in H_{2}SO_{4} is also 0.
For each hydrogen atom
- Valence electrons of hydrogen = It is present in Group I A = 1 valence electron
- Bonding electrons = 1 single bond = 2 electrons
- Non-bonding electrons = no lone pairs = 0 electrons
- Formal charge = 1 – 0 – 2/2 = 1 – 0 – 1 = 1– 1 = 0
∴ The formal charge on each hydrogen (H) atom in H_{2}SO_{4} is 0.
As per the above calculation, zero or no formal charges are present on the bonded atoms in the H_{2}SO_{4} Lewis structure.
Therefore, there is no overall charge present on H_{2}SO_{4}. This denotes that sulfuric acid is a neutral molecule.
Also, check –
- How to draw the H_{2}SO_{4} lewis structure?
- Formal charge calculator
- SO_{3} formal charge
- CO_{2} formal charge
- HCN formal charge
- SO_{4}^{2-} formal charge
- PO_{4}^{3-} formal charge
- SO_{3}^{2-} formal charge
- CN^{–} formal charge
- SO_{2} formal charge
- O_{3} formal charge
- SCN^{–} formal charge
- POCl_{3} formal charge
- NH_{3} formal charge
- CO formal charge
- H_{2}O formal charge
- NH_{4}^{+} formal charge
- H_{3}O^{+} formal charge
- OH^{–} formal charge
- HSO_{4}^{–} formal charge
- ClO^{–} formal charge
- BH_{4}^{–} formal charge
- N_{3}^{–} formal charge
- ClO_{3}^{–} formal charge
- NCO^{–} formal charge
- NO_{3}^{–} formal charge
- NO_{2}^{–} formal charge
- CH_{3} formal charge
FAQ
How can you calculate H_{2}SO_{4} formal charges? |
The formal charges present on the bonded atoms in H_{2}SO_{4} can be calculated using the formula given below: V.E – N.E – B.E/2 Where – ⇒ V.E = valence electrons of an atom ⇒ N.E = non-bonding electrons, i.e., lone pairs ⇒ B.E = bonding electrons |
What is the formal charge on S-atom in H_{2}SO_{4}? |
The central sulfur (S) atom carries zero or no formal charges in H_{2}SO_{4}. |
What are the formal charges on each oxygen atom in H_{2}SO_{4}? |
Zero or no formal charges are present on each of the four oxygen atoms in the H_{2}SO_{4} Lewis structure. |
What are the formal charges on each hydrogen atom in H_{2}SO_{4}? |
Both the H-atoms carry zero or no formal charges in the H_{2}SO_{4} Lewis structure. |
Do all the bonded atoms carry the same formal charges in the H_{2}SO_{4} Lewis structure? |
Yes. All the bonded atoms, i.e., a sulfur atom, two hydrogen atoms, and four oxygen atoms, carry the same, i.e., zero or no formal charges in the H_{2}SO_{4} Lewis structure. |
What is the overall charge present on H_{2}SO_{4}? |
No overall formal charges are present on the H_{2}SO_{4} Lewis structure. Thus, it is a neutral molecule. |
Summary
- The best possible Lewis structure of a molecule is the one in which the bonded atoms carry formal charges as close to zero as possible.
- The formal charge formula is [ V.E – N.E – B.E/2].
- In H_{2}SO_{4}, a zero formal charge is present on the central S-atom.
- Each of the four O-atoms and two H-atoms carries zero formal charges in H_{2}SO_{4}.
- No overall formal charge is present on the H_{2}SO_{4} which denotes that it is a neutral molecule.
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