Draw the Lewis Structure for dichloroethane, C2H4Cl2

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Draw the Lewis Structure for dichloroethane, C2H4Cl2: The two carbon atoms are in the center of this molecule. What is the electron geometry around each carbon atom? What is the molecular geometry around each carbon atom? What is the bond angle around each carbon atom? How many sigma bonds are in this molecule? How many pi bonds are in this molecule? Redraw your Lewis structure to show the three-dimensional shape that you described in parts above. What sort of hybrid orbitals are used by each carbon atom? Is CH2Cl2 polar? If so, add an arrow to your drawing above to show the dipole moment. What is the molarity of a solution made by dissolving 45.9 g of CH2Cl2 in enough water to make 600.0 mL of solution?

The Correct Answer and Explanation is:

Let’s answer each part about dichloroethane (C₂H₄Cl₂) step by step:

1. Lewis Structure of C₂H₄Cl₂

There are two isomers of dichloroethane, but the most common is 1,2-dichloroethane (ClCH₂CH₂Cl).

Lewis Structure:

H   H       H   H
 \ /         \ /
  C — C   or  C — C
 / \         / \
Cl  H       H  Cl

Each carbon has four single bonds: two to hydrogen atoms, one to the other carbon, and one to a chlorine atom.

2. Electron Geometry Around Each Carbon Atom

  • Electron geometry: Tetrahedral
  • Because each carbon is bonded to four atoms (no lone pairs), it adopts a tetrahedral shape.

3. Molecular Geometry Around Each Carbon Atom

  • Molecular geometry: Tetrahedral
  • Same as electron geometry due to lack of lone pairs.

4. Bond Angles Around Each Carbon Atom

  • Ideal tetrahedral bond angle: 109.5°

5. Sigma (σ) and Pi (π) Bonds

  • Each single bond is a sigma bond.
  • Total:
    • 6 C-H σ bonds
    • 2 C-Cl σ bonds
    • 1 C-C σ bond
  • Total sigma bonds = 9
  • Total pi bonds = 0 (no double or triple bonds)

6. 3D Shape Drawing

In 3D, each carbon atom forms a tetrahedron. Here’s a simplified 3D drawing for one carbon:

       Cl
        |
H — C — H
      /
    H

(Use wedges/dashes to show 3D bonds if drawing formally.)

7. Hybrid Orbitals Used

  • Each carbon atom uses sp³ hybrid orbitals.

8. Is CH₂Cl₂ Polar?

Yes, CH₂Cl₂ is polar due to:

  • Asymmetrical geometry.
  • More electronegative chlorine atoms pulling electron density.

Dipole moment: Arrows point from C toward each Cl.

9. Molarity Calculation

Molar mass of CH₂Cl₂ (methylene chloride) =
= 12.01 + (2 × 1.008) + (2 × 35.45)
= 84.93 g/mol

Moles = 45.9 g ÷ 84.93 g/mol ≈ 0.540 moles
Volume = 600.0 mL = 0.600 L
Molarity = 0.540 mol ÷ 0.600 L = 0.900 M

✅ Summary

  • Geometry: Tetrahedral at both carbons.
  • Bond angle: ~109.5°.
  • Sigma bonds: 9.
  • Pi bonds: 0.
  • Hybridization: sp³.
  • Polarity: Polar.
  • Molarity: 0.900 M for CH₂Cl₂ solution.

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