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suppose you have an alkaline buffer consisting of 0.2 M aq ammonia 0.1M ammonium

ID: 515932 • Letter: S

Question

suppose you have an alkaline buffer consisting of 0.2 M aq ammonia 0.1M ammonium chloride. What is the pH of the solution

****calculate the pH of a 0.5M solution of KCN.

****how do contentraion/volumes of the buffer affect the buffer capcaity

please help. show work

Chemistry 106 106 Name: Post-Lab Assessment Questions (20 points): 1. (4 pts) What is the hydronium ion concentration and pH of a 0.10 M solution of hypochlorous acid, Ka 3.5 x 10-8? 2. (4 pts) Suppose you have an alkaline buffer consisting of 0.20 M aqueous ammonia (NH3) and 0.10 M ammonium chloride (NH4ci). What is the pH of the solution? 3. (4 pts) Calculate the pH of a 0.500 M solution of KCN. Ka for HCN is 5.8 x 10.10 4. (8 pts) How do the concentration/volumes of the buffer affect the buffer capacity? E.g. 50.0 mL of 0.10 M acetic acid solution with 50.0 mL of 0.10 M sodium acetate solution vs. the buffer you made in the lab (25.0 mL of 0.10 M acetic acid solution with 25.0 mL of 0.10 M sodium acetate solution)

Explanation / Answer

1)

Ka = 3.5 x 10^-8

concentration C = 0.10 M

[H+] = sqrt (Ka x C)

        = sqrt (3.5 x 10^-8 x 0.1)

        = 5.92 x 10^-5 M

[H3O+] = 5.9 x 10^-5 M

pH = -log [H3O+]

    = -log ( 5.9 x 10^-5)

    = 4.23

pH = 4.23