A buffer is 0.25 M in CH 3 COOH and 0.56 M in CH 3 COONa . What is the value of pH if 0.006 mol of HCl is added to 0.300 L of a buffer solution? [ pK a ( CH 3 COOH ) = 4.7 ] ( lo g 102 = 0.3 )

Question

A buffer is 0.25 M in CH 3 ​ COOH and 0.56 M in CH 3 ​ COONa . What is the value of pH if 0.006 mol of HCl is added to 0.300 L of a buffer solution? [ pK a ​ ( CH 3 ​ COOH ) = 4.7 ] ( lo g 102 = 0.3 )

TestHub · Accepted Answer

Number of moles of CH 3 ​ COOH = 0.25 × 0.3 = 0.075 moles Number of moles of CH 3 ​ COO − = 0.56 × 0.3 = 0.168 ∴ Number of moles of CH 3 ​ COO − left = 0.168 − 0.006 = 0.162 Final number of moles of CH 3 ​ COOH = 0.075 + 0.006 = 0.081 ∴ p H = 4.7 + lo g 0.081 0.162 ​ .

Chemistry - Ionic Equilibrium Question with Solution | TestHub

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