posted by Delli .
The pKa values of acetylene, ehtylene and ethane are 25, 44 and 50 respectively. This means that acetylene is the strongest acid of the three.Explain the order of acidity for the above hydrocarbons
The triple bond of acetylene makes the C atom slightly negative and H slightly positive and the polar bond acts as an acid, although a weak one. Ethylene works the same way but the C atom is less negative, the bond is less polar, and the acidity of ethylene is less than that of acetylene. The same reasoning holds for ethane and the C-C single bond.