Respuesta :
Explanation:
Citric acid upon dissociation given three hydrogen ion that is, citric acid is a triprotic acid.
It is given that volume of juice is 20 ml and concentration of NaOH is 0.165 M.
Initial volume = 1.72 ml, Final volume = 15.51 ml
Hence, volume of the base will be calculated as follows.
[tex]V_{base} = V_{final} - V_{initial}[/tex]
= (15.51 - 1.72) ml
= 13.79 ml
Now, moles of NaOH will be calculated as follows.
No. of moles = [tex]Molarity \times Volume[/tex]
= [tex]0.165 M \times 13.79 ml[/tex]
= 2.275 mmol
As, 1 mol of citric acid = 3 mol of NaOH
Hence, moles of citric acid will be calculated as follows.
Mole of citric acid = [tex]\frac{1}{3} \times 2.275 mmol[/tex]
= 0.758 mmol
Since, molar mass of citric acid is 192.124 g/mol. Hence, mass of citric acid will be calculated as follows.
Mass = No. of moles × Molar mass
= 0.758 mmol × 192.124 g/mol
= 145.72 mg
Thus, we can conclude that there is 145.72 mg of citric acid present per mL of juice.
