What happens when a small amount of HCl is added to a buffer solution containing NH₃ and NH₄Cl?

A 1.00 L buffer solution is made with 0.500 mol of ammonia (NH₃) and 0.600 mol of ammonium chloride (NH₄Cl).The pKa of NH₄⁺ is 9.25. What is the pH of the solution after the addition of 0.100 mol of HCl. Hint:  Assume no change in volume upon addition of HCl

Which of the following titrations would produce a solution with a basic pH at equivalence point?

What is the pH of a buffer made from 0.45 mol of HCN and 0.20 mol of NaCN in 2.0 L of solution? Hint: The Ka of hydrogen cyanide, HCN, is 4.9 × 10⁻10.

Which of the following titrations would produce a solution with an acidic pH at the equivalence point?

What is the pH of a buffer made from 0.15 mol of HF and 0.55 mol of KF in 2.0 L of solution? Hint: The Ka of hydrofluoric acid, HF, is 6.8 × 10⁻4.

In which of the following aqueous solutions would you expect the solubility of Fe(OH)₃ to be the greatest? Hint: Consider the factors that affect solubility.

What is the molar solubility (in M) of magnesium hydroxide (Mg(OH)₂) in water? Hint: Ksp of Mg(OH)₂ = 1.5 × 10⁻11

Which of the following additions will suppress the dissociation of ammonia (NH3) in water?  Addition of NaOH Addition of NaCl Addition of NH4Cl Addition of HCl Hint: Consider the common ion effect and how it would change the percent ionization of the weak acid. 

According to the additional assigned reading, what does  ERS mean and why is it important in early education?