CHM116 week 4 Mon probs

CHM116 week 4 Mon probs - and the final pH after adding...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Use an ICE table to calculate the pH of a solution that is 0.195 M in CH 3 NH 2 (methyl amine) and 0.105 M CH 3 NH 3 Br (methylammonium bromide). You can solve this using the K a for CH 3 NH 3 + , which equals 2.3 x 10 - 11 . (It’s also possible to use the K b for CH 3 NH 2 , which equals 4.4 x 10 -4 . CHM116 Week 4 Mon 9/20 discussion problems Solve the problem above using the Henderson-Hasselbach equation. (You’ll need to calculate the p K a of methlyammonium ion) 1a. 1b. Can you predict the pH of a solution that is is 0.100 M in CH 3 NH 2 and 0.100 M CH 3 NH 3 Br without doing a calculation? (Otherwise, work it out using the Henderson-Hasselbach equation) 1c. The p K a of HF (hydrofluoric acid) is 3.5. Calculate the pH of 250 mL of a solution that contains 0.2 moles of HF and 0.3 moles of NaF using the H-H equation. 2. Calculate the ratio of CH 3 NH 2 to CH 3 NH 3 Br that would be required to yield a solution with a pH of 10.24 (you’ll need to use the p K a for CH 3 NH 3 + that you determined above) 3.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
For each of the following solutions, calculate the initial pH
Background image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: and the final pH after adding 0.010 mol NaOH. 4. a) 250.0 mL of pure water b) 250.0 mL of a buffer solution that is 0.195 M in HCOOH (formic acid) and 0.275 M in KCOOH (potassium formate). The K a of HCOOH = 1.8 x 10-4 . Determine whether or not the mixing of each of the two solutions indicated below will result in a buffer. Explain why or why not. 5. a) 75.0 mL of 0.10 M HF; 55.0 mL of 0.15 M NaF b) 150.0 mL of 0.10 M HF; 135.0 mL of 0.175 M HCl c) 165.0 mL of 0.10 M HF; 135.0 mL of 0.050 M KOH d) 125.0 mL of 0.15 M CH 3 NH 2 ; 120.0 mL of 0.25 M CH 3 NH 3 Cl e) 105.0 mL of 0.15 M CH 3 NH 2 ; 95.0 mL of 0.10 M HCl The fluids within cells are buffered by H 2 PO 4-and HPO 4 2-. 6. a) Calculate the ratio of H 2 PO 4-and HPO 4 2- required to maintain a pH of 7.1 in a cell. (p K a of H 2 PO 4-is 7.2) b) Could a buffer system employing H 3 PO 4 as the weak acid and H 2 PO 4-as the weak base be used as a buffer system within cells? Explain...
View Full Document

Page1 / 2

CHM116 week 4 Mon probs - and the final pH after adding...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online