# What is the general formula of an unsaturated hydrocarbon?

Jun 11, 2017

Well, a saturated hydrocarbon has general formula ${C}_{n} {H}_{2 n + 2}$...

#### Explanation:

And try it out: methane, $C {H}_{4}$; ethane, ${C}_{2} {H}_{6}$; propane..... Are these species in accord with the formula? What is $n$ in each molecule?

Each so-called $\text{degree of unsaturation}$ corresponds to a DOUBLE BOND or a RING-JUNCTION. A 6-membered ring thus has the formula ${C}_{6} {H}_{12}$, ethylene, an olefin, has the formula ${C}_{2} {H}_{4}$.

And thus the general formula for olefins or rings is ${C}_{n} {H}_{2 n}$.

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