The pK, value for H2S is 7.00. What mole ratio of NaHS to H2S is needed to prepare a buffer with a pH of 7.31? [HS ] (H2S]

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**The pKa value for H₂S is 7.00. What mole ratio of NaHS to H₂S is needed to prepare a buffer with a pH of 7.31?**

\[ \frac{[\text{HS}^-]}{[\text{H}_2\text{S}]} = \]

### Explanation for Educational Website

This problem involves the preparation of a buffer solution using sodium hydrogen sulfide (NaHS) and hydrogen sulfide (H₂S). To determine the required mole ratio of NaHS to H₂S to achieve a specific pH, one can use the Henderson-Hasselbalch equation:

\[ \text{pH} = \text{pKa} + \log \left( \frac{[\text{Base}]}{[\text{Acid}]} \right) \]

Where:
- pH is the desired pH of the buffer solution.
- pKa is the acid dissociation constant of the weak acid (H₂S in this case).
- [Base] is the concentration of the base form (HS⁻).
- [Acid] is the concentration of the acid form (H₂S).

In this case:
- pH = 7.31
- pKa = 7.00

Using the Henderson-Hasselbalch equation, the calculation becomes:

\[ 7.31 = 7.00 + \log \left( \frac{[\text{HS}^-]}{[\text{H}_2\text{S}]} \right) \]

Solving for the ratio \(\frac{[\text{HS}^-]}{[\text{H}_2\text{S}]}\):

\[ 7.31 - 7.00 = \log \left( \frac{[\text{HS}^-]}{[\text{H}_2\text{S}]} \right) \]
\[ 0.31 = \log \left( \frac{[\text{HS}^-]}{[\text{H}_2\text{S}]} \right) \]
\[ 10^{0.31} = \frac{[\text{HS}^-]}{[\text{H}_2\text{S}]} \]

Using a calculator, we find:

\[ \frac{[\text{HS}^-]}{
Transcribed Image Text:The text in the image is as follows: **The pKa value for H₂S is 7.00. What mole ratio of NaHS to H₂S is needed to prepare a buffer with a pH of 7.31?** \[ \frac{[\text{HS}^-]}{[\text{H}_2\text{S}]} = \] ### Explanation for Educational Website This problem involves the preparation of a buffer solution using sodium hydrogen sulfide (NaHS) and hydrogen sulfide (H₂S). To determine the required mole ratio of NaHS to H₂S to achieve a specific pH, one can use the Henderson-Hasselbalch equation: \[ \text{pH} = \text{pKa} + \log \left( \frac{[\text{Base}]}{[\text{Acid}]} \right) \] Where: - pH is the desired pH of the buffer solution. - pKa is the acid dissociation constant of the weak acid (H₂S in this case). - [Base] is the concentration of the base form (HS⁻). - [Acid] is the concentration of the acid form (H₂S). In this case: - pH = 7.31 - pKa = 7.00 Using the Henderson-Hasselbalch equation, the calculation becomes: \[ 7.31 = 7.00 + \log \left( \frac{[\text{HS}^-]}{[\text{H}_2\text{S}]} \right) \] Solving for the ratio \(\frac{[\text{HS}^-]}{[\text{H}_2\text{S}]}\): \[ 7.31 - 7.00 = \log \left( \frac{[\text{HS}^-]}{[\text{H}_2\text{S}]} \right) \] \[ 0.31 = \log \left( \frac{[\text{HS}^-]}{[\text{H}_2\text{S}]} \right) \] \[ 10^{0.31} = \frac{[\text{HS}^-]}{[\text{H}_2\text{S}]} \] Using a calculator, we find: \[ \frac{[\text{HS}^-]}{
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