Question

What is the general formula of an unsaturated hydrocarbon?

Answer 1

Well, a saturated hydrocarbon has general formula `C_nH_(2n+2)`...

Explanation:

And try it out: methane, `CH_4`; ethane, `C_2H_6`; propane..... Are these species in accord with the formula? What is `n` in each molecule?

Each so-called `"degree of unsaturation"` corresponds to a DOUBLE BOND or a RING-JUNCTION. A 6-membered ring thus has the formula `C_6H_12`, ethylene, an olefin, has the formula `C_2H_4`.

And thus the general formula for olefins or rings is `C_nH_(2n)`.

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