Answer:
Explanation:
Formula for pH of a buffer solution
pH = pKa + log ( moles of sodium benzoate / moles of benzoic acid)
pKa of benzoic acid = 4.2
Volume of solution is 1.5 L .
moles of sodium benzoate = .29 x 1.5 = .435 moles
moles of benzoic acid = 1.5 x .34 = .51 moles
Addition of HCl will reduce concentration of salt and increase concentration of acid
moles of sodium benzoate after addition of HCl = .435 - .054 = .381 moles
moles of benzoic acid = .51 + .054 = .564 moles
resultant pH = 4.2 + log ( .381 / .564 )
= 4.2 + log .6755
= 4.029
concentration of H⁺ or H₃O⁺ = [tex]10^{ - 4.029 }[/tex]
= 9.35 X 10⁻⁵ M .
The concentration of the solution after adding 0.054 mol HCl to the final volume is [tex]9.35 \times 10^-^5 M .[/tex]
Concentration is the amount of substance present in a specific place.
Calculate the moles of sodium benzoate
The mass of sodium benzoate is 0.29 M
The final volume is 1.5 L
0.29 × 1.5 = 0.435 moles
Now, moles of HCl after adding HCl
0.435 – 0.054 = 0.381
Moles of benzoic acid
0.51 + 0.054 = 0.564 moles
By the formula of pH
pH = pKa + log ( mol of bezoate / mol of benzoic acid)
pKa value is 4.2
Putting the values
[tex]4.2 + log \dfrac{0.381}{0.564} \\\\4.2 + log 0.6755\\\\log = 4.029[/tex]
The concentration of H+ is [tex]10^-^4^.^0^2^9[/tex] = [tex]9.35 \times 10^-^5 M .[/tex]
Thus, the concentration is [tex]9.35 \times 10^-^5 M .[/tex]
Learn more about concentration
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