Determine the solution with the greatest buffer capacity among the representations of solutions shown below containing one or more of the following components: H₂A, KHA, and K₂A, where H₂A is a weak diprotic acid. Note that K⁺ ions and water were omitted from the representation for clarity.

Determine what happens to the pH (increases, decreases, or remains the same) of a buffer solution containing equal concentrations of C₆H₇O₇⁻ and C₆H₆O₇²⁻on the addition of each of the following: 

(a) K₃C₆H₅O₇

(b) NaBr

(c) C₆H₈O₇

(d) HCl 

(e) K₂C₆H₆O₇ 

(f) NaOH

The following diagram represents four different solutions that may contain any of these four species in varying concentrations: H₂A, KHA, and K₂A.

K⁺ ions are not shown for clarity. Identify which of these solutions is a buffer.

A sample mixture of HCl and H₃AsO_4, with a volume of 50 mL, was titrated against 0.250 M NaOH. What indicators would be suitable to signal the equivalence points if the first and second equivalence points were reached after 95 mL and 140 mL of the base were consumed, respectively?

Bromcresol purple is a weak acid and can act as an acid-base indicator. The yellow acidic form is equal in amount to the purple base form when the pH is equal to 6.3. Determine the pK_a for bromcresol purple.  

An unknown solution turns yellow when bromocresol green is added. It turns red when propyl red is added. What information can be established about the solution?

Bromophenol blue is an acid-base indicator with a pK_a of 4.0. Its color changes from yellow to blue going from its acidic form to its basic form. What color will the solution appear when several drops of this indicator are placed in a 50.0 mL of 0.450 M HBr solution? What pH range will the indicator change color when 0.150 M KOH is slowly added to the solution?

Based on the following qualitative analysis flowchart, how can you separate Bi³⁺ ion and Ba²⁺ ion contained in a solution?

A 15.0 mL sample of a solution is tested for Cl^– ions. Two drops (1 drop ≈ 0.2 mL) of 0.15 M AgNO₃ were added to the solution. Calculate the minimum mass (in g) of the Cl^– ion that should be present for AgCl(s) (K_sp = 1.8 × 10^–10) to form.

Which of the following statements is true regarding the removal of impurities?

i. No filtration process is available to filter dissolved nitrates and phosphates

ii. Activated carbon filtration or aeration can filter trihalomethanes

iii. Fine sand filtration can filter coarse sand

iv. Precipitation with aluminum hydroxide can filter bacteria and finely divided particles

Based on the quantitative analysis, the addition of H₂S can separate Pb²⁺, Cu²⁺, and Cd²⁺ from other cations present in a solution. What is the S²⁻ ion concentration needed to start the precipitation of (i) Pb²⁺, (ii) Cu²⁺, and (iii) Cd²⁺ ions if each of the metal ions has a concentration of 0.020 M? When Cu²⁺ starts to precipitate, what fraction of Cd²⁺ is still left in the solution?

K_sp PbS = 7.0×10⁻²⁹, K_sp CuS = 8.0×10⁻³⁷, K_sp CdS = 1.0×10⁻²⁸

Determine the cation that will precipitate first if potassium carbonate is used to precipitate one of the cations in a solution that contains 0.025 M Mn²⁺ and 0.050 M Zn²⁺. Calculate the minimum concentration of K₂CO₃ that will start the precipitation of the cation.

A solution is created by mixing 0.20 M Ni(CH₃COO)₂, 0.30 M HNO₃ and 0.20 M H₂S. 

(i) Will NiS precipitate out of the solution? (K_spa NiS = 3.2) 

(ii) If the pH of the solution is increased to 7 using a phosphate buffer, will NiS precipitate out of the solution? 

Pyrophosphate (P₂O₇⁴⁻) is added to laundry detergents to prevent the precipitation of insoluble calcium and magnesium salts. Consider a scenario where Na₂H₂P₂O₇ is added to the solution and we're trying to dissolve Ca(OH)₂ salts because Ca²⁺ ions form a soluble complex with pyrophosphate.

(a) Given that the K_sp for Ca(OH)₂ is 4.7×10^–6 and the K_f for [Ca(P₂O₇)]²⁻ is 4.0×10⁴, determine the equilibrium constant (K_eq) for the reaction.

(b) What is the molar solubility of Ca(OH)₂ in 2.50 M Na₂H₂P₂O₇ solution?

[K_a2 H₂P₂O₇^2– = 2.51×10^–7; K_a3 HP₂O₇^3– = 3.89×10^–10]