Find the pH of a buffer that consists of 1.6 M sodium phenolate (C6H5ONa) and 1.0M phenol (C6H5OH). (pKa of phenol=10.00)
To find the pH of the buffer, we need to use the Henderson-Hasselbalch equation:
pH = pKa + log ([A-] / [HA])
Here, [A-] represents the concentration of the conjugate base (sodium phenolate), and [HA] represents the concentration of the weak acid (phenol).
Given:
- [A-] = 1.6 M (sodium phenolate)
- [HA] = 1.0 M (phenol)
- pKa = 10.00 (phenol)
Substituting the values into the Henderson-Hasselbalch equation:
pH = 10.00 + log (1.6 / 1.0)
pH = 10.00 + log (1.6)
To find the result, let's calculate the logarithm:
log (1.6) ≈ 0.2041 (rounded to 4 decimal places)
Now, substitute the value back into the equation:
pH = 10.00 + 0.2041
pH ≈ 10.2041
Therefore, the pH of the buffer is approximately 10.2041.
To find the pH of a buffer, we need to use the Henderson-Hasselbalch equation, which is given by:
pH = pKa + log(base/acid)
In this case, the sodium phenolate (C6H5ONa) will act as the base and phenol (C6H5OH) will act as the acid. The pKa value of phenol is given as 10.00.
Now, let's calculate the base/acid ratio using the given concentrations:
Base/acid = (concentration of base) / (concentration of acid)
Base/acid = 1.6 M / 1.0 M
Base/acid = 1.6
Now, substitute the values into the Henderson-Hasselbalch equation:
pH = 10.00 + log(1.6)
pH = 10.00 + 0.2041 (approximately)
Therefore, the pH of the buffer is approximately 10.2041.