Which of the following combinations would make a buffer with pH closest to 9.0? HClO2   Ka = 1.1 × 10-2 NH3   Kb = 1.8 × 10-5 HNO2   Ka = 7.2 × 10-4 C5H5N   Kb = 1.5 × 10-9   Equal volumes of 0.10 M HCl and 0.10 M NaCl       Equal volumes of 0.10 M HNO2 and 0.10 M NaNO2       Equal volumes of 0.10 M NH4Cl and 0.10 M NH3       Equal volumes of 0.10 M HClO2 and 0.10 M NaClO2       Equal volumes of 0.10 M C5H5NHCl and 0.10 M C5H5N

15.0 mL of a buffer is made by mixing 10.0 mL of 0.10 M HF and 5.0 mL of 0.10 M NaOH solution. What is the pH of this buffer after 0.24 mL of 1.0 M sodium hydroxide are added to it? The Ka for HF is 6.8 x 10-4.

Select the combination that results in the most effective buffer? O 0.800 M HNO2; 0.799 M NANO2 O 0.800 M HCOOH; 0.100 M KCOOH 0.700 M HNO3; 0.599 M NaNO3 O 0.100 M HBr; 0.899 M NH4Br

Which of the following aqueous mixtures will result in a buffer with a pH higher than 7.0? (For HCNO, Ka = 2.2×10-4, for NH3, Kb = 1.8×10-5 ) 10 mL of 0.1 M NH3 + 10 mL of 0.1 M HCl  10 mL of 0.1 M NH3 + 10 mL of 0.1 M HCNO 10 mL of 0.1 M NH3 + 5.0 mL of 0.1 M HCl (Correct answer) 10 mL of 0.1 M HCNO + 10 mL of 0.1 M NaOH 10 mL of 0.1 M HCNO + 5.0 mL of 0.1 M NaOH   please explain. thanks!

Consider the following reaction. O + 0 CHBr3 Draw the major organic product formed in this reaction. 81 + [**** (CH3)3CO¹K+ • Use the wedge/hash bond tools to indicate stereochemistry where it exists. • Include H atoms at chiral centers only. • Show stereochemistry in a meso compound. If the reaction produces a racemic mixture, just draw one stereoisomer. - √n [F] ?

The acid HX has a pKa of 5.76.  What volume, in mL, of a 0.100 M solution of sodium hydroxide needs to be added to 25.00 mL of a 0.100 M solution of the acid solution to make a buffer with a pH of 5.44?

What ratio of NaCN to HCN is needed to prepare a pH 10.00 buffer? (Ka of HCN is 4.9 × 10⁻¹⁰)

Assuming equal concentrations of conjugate base and acid, which one of the following mixtures is the best choice for making a buffer solution with an optimum pH in the range of 3.1-3.5? O O O NaNO2/HNO2 (K₂ = 4.6 x 10-4) KCH3COO/CH3COOH (K₂ = 1.75 x 10-5) CH3NH2/CH3NH3CI (K₂ = 2.3 x 10-11) NaOCN/HOCN (K₂ = 2.0 x 10-4) NaNO3/HNO3 20