---
title: "Acetylene Structure (C2H2): 3D Model, Formula & Molar Mass | MolDraw"
url: https://www.moldraw.com/molecules/acetylene.html
description: "Structure of Acetylene (C2H2, 26.04 g/mol): rotatable 3D model, 2D skeletal formula, IUPAC name, SMILES, shape, polarity, uses and FAQ."
lang: en
publisher: Scidart Academy
generated: 2026-10-26
---
[MolDraw](https://www.moldraw.com/) › [3D molecule models](https://www.moldraw.com/molecules/) › Acetylene structure

# Acetylene structure and 3D model (C2H2)

Acetylene (ethyne) is the simplest alkyne: two carbons joined by a C≡C triple bond with one hydrogen on each. All four atoms are in a straight line.

**Quick answer:** Acetylene is **C2H2**, molar mass **26.04 g/mol**. Linear and symmetric; non-polar and slightly soluble in water.

Atom labels Hydrogens Spin

Drag to rotate · pinch or scroll to zoom. 3D coordinates: computed with RDKit (ETKDG conformer, force-field optimised).

## Acetylene at a glance

| Formula | C2H2 |
| --- | --- |
| Molar mass | 26.04 g/mol |
| IUPAC name | acetylene |
| Atoms / bonds | 4 / 3 |
| H-bond donors / acceptors | 0 / 0 |
| logP (estimated) | 0.2 |
| SMILES | `C#C` |
| InChIKey | `HSFWRNGVRCDJHI-UHFFFAOYSA-N` |
| PubChem | [6326](https://pubchem.ncbi.nlm.nih.gov/compound/6326) |

![2D structural formula of Acetylene (C2H2)](https://www.moldraw.com/molecules/img/acetylene.svg)

2D structure (skeletal formula) · [Draw it in MolDraw](https://www.moldraw.com/)

## What the 3D model of Acetylene shows

The model contains **4 atoms** (2 heavy atoms and 2 hydrogens) joined by **3 bonds**; in ball-and-stick mode every stick is one bond, and double or aromatic bonds are drawn as multiple sticks. Switch to *space-filling* to see the molecule as its electron cloud, scaled to van der Waals radii: this is the shape other molecules actually "feel". It can donate 0 and accept 0 hydrogen bonds, and its estimated logP of 0.2 means it is fairly balanced between water and fat. Its topological polar surface area is 0 Ų.

## Shape and bond angles

| Atom(s) | Geometry / hybridisation | Angles & lengths |
| --- | --- | --- |
| each carbon | Linear, sp | 180° |
| C≡C bond | Triple bond (σ + 2π) | ≈ 1.20 Å |
| C–H bond | Single bond | ≈ 1.06 Å |

### Is Acetylene polar?

No. It is linear and symmetric, so it has no net dipole. Its C–H bonds are slightly acidic for a hydrocarbon (pKa about 25).

## Elemental composition of C2H2

| Element | Atoms | Mass (g/mol) | Mass % |
| --- | --- | --- | --- |
| Carbon (C) | 2 | 24.022 | 92.26% |
| Hydrogen (H) | 2 | 2.016 | 7.74% |

Calculated from IUPAC standard atomic weights. Check any formula with the [molar mass calculator](https://www.moldraw.com/tools/free-chem-tools/molar-mass-calculator.html).

## Uses of acetylene

- Fuel for oxy-acetylene welding and cutting
- Raw material for vinyl chloride and other chemicals
- Was used in carbide lamps for mining and bicycles

## Interesting facts

- An oxy-acetylene flame can reach over 3000 °C.
- Acetylene is made by adding water to calcium carbide or by cracking hydrocarbons.
- It is stored dissolved in acetone inside cylinders because compressed pure acetylene can explode.

**Drawing structures for your notes?** MolDraw is a free online chemical structure editor for molecules, reactions and lab diagrams.

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## Frequently asked questions

### What is the structure of Acetylene?

Acetylene (ethyne) is the simplest alkyne: two carbons joined by a C≡C triple bond with one hydrogen on each. All four atoms are in a straight line. Its SMILES is C#C.

### Why is acetylene linear?

Each carbon is sp hybridised with two electron domains, which point 180° apart.

### Is acetylene the same as ethyne?

Yes. Ethyne is the systematic name; acetylene is the common name and is accepted by IUPAC.

### What is the chemical formula and molar mass of Acetylene?

Acetylene is C2H2 with a molar mass of 26.04 g/mol. It contains 4 atoms: 2 carbon, 2 hydrogen.

### What is the IUPAC name of Acetylene?

The IUPAC name is acetylene.

### How do I draw Acetylene?

Open the MolDraw editor, paste the SMILES C#C or type "Acetylene" in name search, and the structure is drawn for you. You can then export it as PNG, SVG, MOL or CDXML.

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