When ammonium (NH4+) is placed in water, a chemical reaction occurs and an equilibrium is established as shown below.   NH4+ (aq) + H2O (l)  ⇄  NH3 (aq) + H3O+ (aq) The pKa of NH4+ is 9.25.  Predict whether the acid form (NH4+) or the base form (NH3) is predominant at pH = 7.4.

At this pH, calculate the concentration of each form of maleic acid in the solution at equilibrium. The three forms of maleic acid are abbreviated as H2M,H2M, HM−,HM−, and M2−,M2−, which represent the fully protonated, intermediate, and fully deprotonated forms, respectively.

Calculate the [NH₃] in a solution of 0.480 M ammonium cyanide (NH₄CN). Hint: Use the Ka of HCN (4.9 × 10⁻¹⁰) and the Kb of NH₃ (1.8 × 10⁻⁵) to calculate Kc for the reaction NH₄⁺(aq) + CN⁻(aq) ⇌ NH₃(aq) + HCN(aq).

Reaction:  NaHCO3(aq)  +  HCl(aq)   ®   NaCl(aq)  +  CO2(g)  +  H2O(l)   Methyl orange is a pH indicator. It is yellow above pH 4.4, orange between pH 4.4 and 3.2 and red below pH 3.2.  NaHCO3 is a weak base and it must be acidified to about pH 4 to completely neutralize it.  Why did you test the reaction mixture with this indicator before you began the evaporation step?