Question a on lab write-up: Here is the procedures, data, and lab questions im h

Question

Question a on lab write-up: Here is the procedures, data, and lab questions im having an issue answering. I need help on putting all the pieces together and answering the lab quesstions at the bottom. Thank you!

(Procedures)

NH3 / NH4 buffer

Add NH3/NH4 to 15 mL of the conjugate base (NH3) to the same beaker. You have created a buffer solution. Measure the pH with a meter.

Rinse your cylinder and use it to add 30 mL of distilled water to the buffer solution to dilute its concentration. Measure and record the pH.

(Data from lab)

Buffer used: NH4/NH3 - pH 9.85

Water pH: 9.79

buffer + HCl pH: 9.76

buffer + NaOH: 9.80

(lab questions)

A. What buffer system did you use?

• The buffer used: NH4/NH3

B. What was the pH of the original buffer?

C. What was [H+] in the buffer? (This is equal to conjugate acid Ka)

D. What was the pH of the diluted buffer?

E. What was [H+] in the buffer? (Ka)

Explanation / Answer

A ) buffer : NH4+ / NH3

B) pH of original buffer = 9.85

C) pH = 9.85

   [H+] = 10^-pH = 10^-9.85 = Ka

[H+] = 1.41 x 10^-10 M

D) pH of the diluted buffer = 9.79

E) [H+] = 10^-9.79

   [H+] = 1.62 x 10^-`10 M

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