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If [ClO₂] = 0.903 M, what [HClO₂] is needed to make a buffer of pH 2.7?

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Final answer:

To make a buffer of pH 2.7, you would need a concentration of approximately 0.000013 M of HClO₂.

Step-by-step explanation:

To make a buffer of pH 2.7, we need to use the Henderson-Hasselbalch equation:

pH = pKa + log([A-]/[HA])

Here, pKa is the negative logarithm of the acid dissociation constant, and [A-] and [HA] are the concentrations of the conjugate base and acid, respectively.

In this case, the acid is HClO₂ and the conjugate base is ClO₂. Since we have the concentration of ClO₂ (0.903 M), we can rearrange the equation to solve for [HA]:

2.7 = pKa + log([0.903]/[HA])

Using the pKa value for HClO₂ (approximately 7.53), we can solve for [HA]:

[HA] = [0.903]/10^(7.53-2.7)

[HA] ≈ 0.000013 M

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