rank strongest acid to weakest acid?

Question

rank strongest acid to weakest acid

H3CNH2
CH3C (triple bond) CH
CH2=CHCH3
H20
CH4

i tried to rank them using the Pka values but I couldn't find the pKa value of the alkyne and I thought the H3CNH2 was the strongest but it's not?

Answer 1

The strongest is the triple bond with terminal H. You had that ranked correctly yesterday when you first posted this problem.
Next is double bond with terminal H.
CH3NH2 is an amine and is basic. That will be the weakest acid listed.
You place H2O and CH4. Can you find the pKa values for CH4 and H2O? I think H2O is 16 but I'm not sure my memory is that good and I don't know pKa for CH4. However, the two go between the amine and the double bond with terminal H.

Answer 2

wow.....not even close to the answer....
it was H2O first and then the triple bond, the amine, double bond, and CH4....
:/

Answer 3

I did this same problem on Sapling Learning and I can confirm Anonymous's answer is correct. Now, if only someone can explain why it makes sense. Is it just comparing pKa values?

Answer 4

What is the name to h2c

Answer 5

sp C is more acidic than sp2 C which is more acidic than sp3 C because it is more electronegative relatively. Thus, alkene (triple bond) acidity > alkene > alkane