[abcc]

which is more acidic , ethane or ethene ??
and WHY?
THX

[Yggdrasil]

Hint: The carbons in ethane are sp³ hybridized, but the carbons in ethene are sp² hybridized.  Does this give you any insight into which is more acidic?

[abcc]

Hint: The carbons in ethane are sp³ hybridized, but the carbons in ethene are sp² hybridized.  Does this give you any insight into which is more acidic?

i still havn't any idea~
can you explain more 
confused
thxthx

[Dan]

think about which orbital the -ve charge will reside in in each case.

[abcc]

think about which orbital the -ve charge will reside in in each case.

ooooooo
ethane is more acidic ~
is it becoz the -ive charge ( lone pair e-) donate to the p-orbital of the another carbon
it is just similiar to the hyperconjuncation effect
thxthxthx

[tamim83]

Um, not quite.  Think a bit harder about the hybridization

[Yggdrasil]

Hint #2:  For a molecular orbital you can define a property called the "s-character" of the orbital (for example, sp³ has 1/4 s-character since it is composed of 1 s-orbital and 3 p-orbitals, while an sp orbital has an s-character of 1/2).  Molecular orbitals with different s-characters will have different electronegativities.  Given what you know about s and p orbitals (which one holds on to electrons more strongly?), how do you think s-character affects the electronegativity of the orbital?  Once you figure that out, it should be clear why ethene is more acidic.

[abcc]

thxq, Big HELP

[Dan]

So what answer did you decide on?