Final answer:
The ratio [NO2-]/[HNO2] in the buffer solution with a pH of 3.72 and a pKa of 3.35 for nitrous acid is calculated to be approximately 2.34 using the Henderson-Hasselbalch equation.
Step-by-step explanation:
The question relates to the calculation of the ratio of conjugate base to acid concentration in a buffer solution using the Henderson-Hasselbalch equation. Given the pH of the buffer (3.72) and the pKa of nitrous acid (3.35), we can determine the ratio [NO2-]/[HNO2]. Applying the Henderson-Hasselbalch equation, pH = pKa + log([A-]/[HA]), we can rearrange it to solve for [A-]/[HA]: [A-]/[HA] = 10(pH - pKa). After substituting the given values, [NO2-]/[HNO2] = 10(3.72 - 3.35), which results in a ratio of approximately 2.34. Therefore, the ratio of nitrite ions to nitrous acid in the buffer solution is 2.34.
To find the ratio of [NO₂-] to [HNO₂] in the buffer, we need to use the Henderson-Hasselbalch equation. The Henderson-Hasselbalch equation is:
pH = pKa + log([A-]/[HA])
In this case, [A-] represents the concentration of NO₂- and [HA] represents the concentration of HNO₂. We are given that the pH of the buffer is 3.72 and the pKa for HNO₂ is 3.35. Plugging these values into the Henderson-Hasselbalch equation:
3.72 = 3.35 + log([NO₂-]/[HNO₂])
Simplifying the equation:
log([NO₂-]/[HNO₂]) = 3.72 - 3.35
[NO₂-]/[HNO₂] = 10^(3.72 - 3.35)
Using a calculator, we find that the ratio [NO₂-]/[HNO₂] is approximately 3.981.