D5

A chemistry graduate student is given 125. mL of a 1.60 M dimethylamine ((CH,) NH) solution. Dimethylamine is a weak base with K; = 5.4 × 10¯*. What mass of (CH,) NH,Cl should the student dissolve in the (CH, NH solution to turn it into a buffer with pH = 10.46? You may assume that the volume of the solution doesn't change when the (CH, NH,Cl is dissolved in it. Be sure your answer has a unit symbol, and round it to 2 significant digits.

A chemistry graduate student is given 500. mL of a 1.80M hydrocyanic acid (HCN) solution. Hydrocyanic acid is a weak acid with K,= 4.9 x 10 – 10 What mass of KCN should the student dissolve in the HCN solution to turn it into a buffer with pH =9.70? You may assume that the volume of the solution doesn't change when the KCN is dissolved in it. Be sure your answer has a unit symbol, and round it to 2 significant digits. 国 国 回

Fill out the tables and find pH

Buffer capacity is a measure of a buffer solution's resistance to changes in pH as strong acid or base is added. Suppose that you have 145 mL of a buffer that is 0.300 M in both acetic acid (CH₂COOH) and its conjugate base (CH3COO-). Calculate the maximum volume of 0.170M HCl that can be added to the buffer before its buffering capacity is lost. volume: esc ! 1 ← 2 #3 с $ 4 G Search or type URL 27 20 % MacBook Pro 5 ^ 6 & 7 +00 8 ( 9 ) mL 0 1

Suppose you are asked to prepare a buffer solution for an upcoming experiment using stock solutions of the weak acid and its conjugate base. Use the following information to determine the volumes of weak acid, conjugate base and distilled water you will need to make the buffer solution: You have 1.0 M stock sodium hydrogencarbonate (NaHCO3) solution, pKa=10.33 You also have 1.0 M stock disodium carbonate (NaCO3) solution The final buffer solution should have a concentration of 80 mM, a volume of 500 mL, and a pH of 9.60 First, use the HH equation to calculate the ratio of the two stock solutions you will need to mix together to reach the target pH, and report this ratio. Next, calculate and report the volumes of weak acid, conjugate base and dH2O you will need to prepare the buffer. No sample calculation is necessary. Hints: • Calculate the volume of distilled water by considering the HA and A- stock solutions as a single mixture of 1.0 M buffer. This way, it's easier to calculate the…

GW 18b 1. A 20.0 mL sample of a 0.240 M hydrofluoric acid (HF) solution is titrated with 0.200 M NaOH. Determine: (a) pH of the acid solution before any base is added; (b) volume (in mL) of base needed to get to the equivalence point; (c) pH halfway to equivalence point; (d) pH at equivalence point; (e) pH when 0.100 mL NaOH is added beyond the equivalence point. (K₂ of HF = 7.1 × 104)

For the titration of an aqueous nitrous acid solution, HNO,(aq), with an aqueous strontium hydroxide solution, Sr(OH)2{aq), what do you expect the pH of the solution to be at the equivalence point? O Basic (pH > 7.00) O Unable to determine the pH of the solution at the equivalence point without additional information O Acidic (pH < 7.00) O Neutral (pH = 7.00)

A buffer is made using 100.0 mL of 0.100 M CH3 CH2 COOH (propanoic acid) and 100.0 mL of 0.100 M NACH3 CH2 COO (sodium propanoate). A) Explain in your own words what will occur (at the molecular level) when an nitric acid is added to the buffer? What would be the effect on the pH? B) Explain in your own words what will occur when LIOH is added tot he buffer? What would be the effect on the [H+]?

An aqueous solution contains 0.25 M hydrofluoric acid. One Liter of this solution could be converted into a buffer by the addition of: (Assume that the volume remains constant as each substance is added.) 0.12 mol HCIO4 O0.25 mol Nal O0.26 mol NaF O0.26 mol HCIO4 O0.062 mol Ca(OH)2