Calculate the pH of the buffer that results from mixing 60.0 mL of 0.25 M HCHO2(pKa= 3.74) and 15.0 mL of 0.500 M NaCHO

Explanation:

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In this case, since the formic acid (HCHO2) is a weak acid and it is mixed with its conjugate base (CHO2⁻) in the form of NaCHO2, we can compute the pH via the Henderson-Hasselbach equation:

Whereas the concentration of both acid and base are computed considering final total volume of 75.0 mL after adding the volume of each solution as shown below:

And the resulting concentrations upon the final volume:

Thus, the pH is:

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it is stable as it is in group 0 which have full outer shells of electrons