[ifrah]

why are alkynes i.e.ethyne acidic in nature??

[KritikalMass]

http://www.cliffsnotes.com/WileyCDA/CliffsReviewTopic/Alkynes-Acidity.topicArticleId-22667,articleId-22632.html

http://www.chem.ucalgary.ca/courses/351/Carey5th/Ch09/ch9-2.html

[catalyst]

From my understanding acidity has to do with hydrogen atoms, and bases have to do with hydroxide ions (OH^-).

So it's not completely out of the ordinary that alkynes, which are a type of hydrocarbon (an aliphatic hydrocarbon to be exact) might exhibit some of these characteristics.

I believe the reason WHY it's more acidic when compared to other hydrocarbons has something to do with its electron structure in a way that it is more willing to give up its hydrogen.

Hope that helps.