# Between ethene and propene which is more acidic and why?

Between ethene and propene, which is more acidic and why? If they are they are the same then why so?
Their $\mathrm{p}K_{\mathrm{a}}$ is the same $\mathrm{p}K_{\mathrm{a}}$ as ~44.

• May 1 '15 at 15:38
• I dont think that quite answers my question.
– user14857
May 1 '15 at 18:37

The difference between there acidity arises only due to the difference in inductive effect[or the electron donating capacity of the alkyl group] of the alkyl group attached to the $\ce{C=C}$ in both the cases.

By this site there exists a difference of total one unit

The anions formed are $\ce{H3C-CH=CH-}$ and $\ce{H2C=CH-}$ . In the former one the anion or the negative charge on the anion is destabilized by the electron donating ability or the inductive effect of $\ce{CH3-}$, hence it is less stable and less rapidly formed and hence less acidic.
Why $\ce{H3C-}$ has electron donating effect?
$\ce{H3C-CH=CH-}$ is less stable due to presence of above factor.