* Electron Density: The nitrogen atoms in both hydrazine and ammonia have a lone pair of electrons, which is responsible for their basicity. However, in hydrazine, the electron density on the nitrogen atom is slightly lower due to the presence of the second nitrogen atom, which can withdraw some electron density through the N-N bond.
* Inductive Effect: The electron-withdrawing effect of the second nitrogen in hydrazine, known as the inductive effect, weakens the electron density on the nitrogen atom, making it less likely to donate its lone pair of electrons and act as a base.
* pKa Values: The pKa values of the conjugate acids of these compounds further support this observation. The pKa of the ammonium ion (NH₄⁺) is 9.25, while the pKa of the hydrazinium ion (N₂H₅⁺) is 8.1. A higher pKa indicates a weaker acid, which means the corresponding base (ammonia in this case) is stronger.
Therefore, ammonia is more basic than hydrazine.
It's important to remember that the strength of a base depends on its ability to donate electrons and form a bond with a proton (H⁺). While both ammonia and hydrazine have a lone pair of electrons, the electron density and the inductive effect in hydrazine make it less effective at donating those electrons and acting as a base.
