Which one is the conjugate acid (HA) and base (A-) for NH2 and NH3+?
Your formulas are actually wrong which may be the reason why you have a hard time figuring out the conjugate acid and conjugate base. NH2 and NH3+ don’t exist. NH2 is NH2^- (charge is negative one) and because NH3+ does not exist, maybe you are referring to NH4^+ (charge is positive one). Since the ammide ion, NH2^- is negatively charged, it is the Bronsted-Lowry base and would accept the proton (H+) to form the conjugate acid, NH3. Since the ammonium ion, NH4^+ is positively charged, it is the Bronsted-Lowry acid (has a lot of Hs) and would lose the proton (H+) to form the conjugate base, NH3.
