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