Question

If 45 mL of .25 M HCl is required to completely neutralize 25.o mL of NH3, what is the concentration of the NH3 solution?

Answer 1

The equation is NH3 + HCl ==> NH4Cl

mol HCl = M x L = ?
mols NH3 = mols HCl (from the equation which shows 1 mol NH3 reacts with 1 mol HCl)
Then M NH3 = mols NH3/L NH3. You have mols and L, solve for M.