Would a solution that is .20 M in ammonia and .20 M in ammonia chloride be a buf

Question

Would a solution that is .20 M in ammonia and .20 M in ammonia chloride be a buffer? Explain. Make a drawing showing the composition of this solution. Write the Henderson-Hasselbalch equation for a basic buffer solution and calculate the pH.

Explain what happens when a small amount of acid is added to the ammonia/ ammonia chloride solution? Use the illustration to help the reasoning process as well as include another illustration. Predict the calculated pH after the additon of 10 mL of .10 M HCl to 65 mL of the ammonia/ ammonia chloride solution.

Explanation / Answer

pH = pKa + log([base]/[acid])
pKa = 9.25

Now, we can use:
pH = 9.25 + log([base]/[acid])

We have 0.2 M ammonia, the base, and 0.2 M ammonium ions,
pH = 9.25 + log(0.2/0.2)
pH = 9.25 + 0
pH = 9.25

moles of salt = moles of ammonia = 0.2*0.065 =0.013

when 10 mL of 0.1M of HCl is added then ammonia concentration decreases and salt concentration increases.moles of HCl = 0.1*0.01 = 0.001 moles.

moles of ammonia after addition of HCl = 0.013 - 0.001 = 0.012

moles of ammonium chloride after addition of HCl = 0.013+0.001 = 0.014

pH = pKa + log(ammonium chloride/ammonia)

     = 9.25 +log(0.014/0.012)

     = 9.32

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