58. Which buffer system is the best choice to create a buffer with PH = 9.00? For the best system, calculate the ratio of the masses of the buffer components required to make the buffer. HF/KF NH3/NH4Cl HNO2/KNO2 HCIO/KCIO

928 O Acids and Bases Calculating the composition of a buffer of a given pH A chemistry graduate student given 250. mL of a 1.70M nitrous acid (HNO₂) solution. Nitrous acid is a weak acid with K-4.5 x 10 What mass of NaNO, should the student dissolve in the HNO, solution to turn it into a buffer with pH = 3.10? You may assume that the volume of the solution doesn't change when the NaNO, is dissolved in it. Be sure your answer has a unit symbol, and round it to 2 significant digits. Explanation Check X 15 Reading schedule S tv Lara V 9 da Ad 19.6 Reduction Po zoom Aa

What would be the molar ratio of cyanic acid (HCNO)/sodium cyanate (NaCNO) buffer having a pH of 4.80 ? [K a(HCNO) = 2.0 × 10 –4]       11.6 mol NaCNO to 1.0 mol HCNO     12.6 mol NaCNO to 1.0 mol HCNO     None of the above     13.6 mol NaCNO to 1.0 mol HCNO     10.6 mol NaCNO to 1.0 mol HCNO

5, Which of the following pairs will not form a buffer when mixed together in an aqueous solution?   a. Na2HPO4 and KH2PO4   b. HF and NaF   c. NaCl and NaOH   d. HOCl and NaOCl   e. all of the above are buffers

Which of the following acid/base pairs would be best for making a buffer with a pH of 9.50? HCN and NaCN H2SO3 and NaHSO3 H2CO3 and NaHCO3 NaH2PO4 and NA2HPO4 HO2Н3О2 and NaC2Hз02

0.50 M solutions of each weak acid in the table are available. Choose an acid solution and determine what volume, in mL, of a 1.00 M NaOH solution should be added to 1.00 L of the acid solution to create a buffer with pH = 6.88.   acid/base pairs to use: Ka pKa HCO2H/NaHCO2 1.8×10-4 3.74 H2CO3/NaHCO3 4.2×10-7 6.38 HBO3/NaH2BO3 7.3×10-10 9.14 NaHCO3/Na2CO3 4.8×10-11 10.32   HCO2H/NaHCO2 H2CO3/NaHCO3 H3BO3/NaH2BO3 NaHCO3/Na2CO3  ---------mL NaOH

A solution of a weak acid is titrated with a standard solution of a strong base. The progress of the titration is followed with a pH meter. Which of the following observations best describes what would occur? Initially the pH of the solution increases slowly, and then it increases much more rapidly, before increasing slowly again At the equivalence point, the pH is 7 The pH of the solution gradually decreases throughout the experiment After the equivalence point, the pH becomes constant because this is the buffer

Which of the following would make the best buffer with the highest "buffer capacity"? 100 mM NH4+ and 5 mM NaOH 100 mM NH4+ and 10 mM NaOH 100 mM NH4+ and 25 mM NaOH 100 mM NH4+ and 50 mM NaOH 100 mM NH4+ and 100 mM NaOH

In a particular titration experiment a 25.0 mL sample of an unknown H2SO4 required 30.0 mL of 0.200 M NaOH for the end point to be reached.   What is the concentration of the acid?   A 0.120 M   B 0.167 M   C 0.240 M   D 0.333 M

A buffer solution is prepared by dissolving 1.000 g of sodium acetate (CH3COONa) into 100.00 of a 0.100 M solution of acetic acid. Then 3.00 1.00 M solution of sodium hydroxide is added to the acetic acid/sodium acetate buffer solution. What is the pH of the solution after adding NaOH ? 4 significant dig