Question

What is the difference between NH4OH AND NH3

Answer 1

Not much mate, and in fact we could write in for [math]NH_{4}OH[/math] the formula [math]NH_{3}•H_{2}O[/math]. The point is that ammonia is VERY soluble in water, and it should be, because like water, it is strongly hydrogen bonding, and the concentrated ammonia we use in the lab is AN AQUEOUS solution that is approx. [math]15•mol•L^{-1}[/math] with respect to ammonia.

And in AQUEOUS solution the ammonia undergoes the acid base equilibrium…

[math]NH_{3} + H_{2}O(l) ⇌ NH_{4}^{+} + HO^{-}[/math]

For which [math]pK_{b}=4.75[/math].