Question

1. john needs to create a buffered solution at a ph of 3.5 for his biomedical laboratory

Answer 1

Answer:

Use a ratio of 0.44 mol lactate to 1 mol of lactic acid  

Explanation:

John could prepare a lactate buffer.

He can use the Henderson-Hasselbalch equation to find the acid/base ratio for the buffer.

$\text{pH} = \text{pK}_{\text{a}} + \log\dfrac{\text{[A ^{-} ]}}{\text{[HA]}}\\\\3.5 = 3.86 + \log\dfrac{\text{[A ^{-} ]}}{\text{[HA]}}\\\\\log\dfrac{\text{[A ^{-} ]}}{\text{[HA]}} = 3.5 - 3.86 = -0.36\\\\\dfrac{\text{[A ^{-} ]}}{\text{[HA]}} = 10^{-0.36} = \mathbf{0.44}$

He should use a ratio of 0.44 mol lactate to 1 mol of lactic acid.

For example, he could mix equal volumes of 0.044 mol·L⁻¹ lactate and 0.1 mol·L⁻¹ lactic acid.