Respuesta :
Answer:
The unknown acid is citric acid.
Explanation:
Based on the reactions:
Citric acid: H3C6H5O7(aq) + 3NaOH (aq) → 3H2O (l) + Na2C6H5O7 (aq)
Tartaric acid: H2C4H4O6 (aq) + 2NaOH (aq) → 2H2O (l) + Na2C4H4O6 (aq)
0.956g of sample if tartaric acid requires:
0.956g × (1mol / 150,087 g) = 0.006370 moles of tartaric acid. As 1 mole reacts with 2 moles of NaOH:
0.006370 moles of tartaric acid × (2 mol NaOH / 1 moles tartaric acid) = 0.0127 moles of NaOH. As the concentration of the NaOH is 0.513M:
0.0127 moles of NaOH × (1L / 0.513mol) = 0.0248L ≡ 24.8mL
Now, 0.956g of citric acid requires:
0.956g × (1mol / 192,124g) = 0.004976 moles of citric acid. As 1 mole reacts with 3 moles of NaOH:
0.004976 moles of citric acid × (3 mol NaOH / 1 moles tartaric acid) = 0.0149 moles of NaOH. As the concentration of the NaOH is 0.513M:
0.0149 moles of NaOH × (1L / 0.513mol) = 0.0291L ≡ 29.1mL
As the titration requires 29.1mL of the base, the unknown acid is citric acid.
Answer:
Explanation:
Equation of the reaction:
Citric acid: H3C6H5O7(aq) + 3NaOH (aq) ---> 3H2O (l) + Na2C6H5O7 (aq)
Tataric Acid: H2C4H4O6 (aq) + 2NaOH (aq) ---> 2H2O (l) + Na2C4H4O6 (aq)
Given:
Mass of solid acid = 0.956 g
Volume of base, vb = 29.1 ml
Concentration of base, cb = 0.513 M
Number of moles of NaOH = concentration × volume
= 0.513 × 29.1 × 10^-3
= 0.0149 moles
From equation 1,
By stoichiometry, 1 mole of citric acid will react with 3 moles of NaOH. Therefore, number of moles of citric acid = 0.0149/3
= 0.00498 moles
Molar mass of citric acid, H3C6H5O79 = (8 × 1) + (6 × 12) + (79 × 16)
= 192 g/mol
Mass = number of moles × molar mass
= 192 × 0.00498
= 0.956 g
Therefore the solid acid is citric acid.
