Respuesta :
Answer:
The unknown acid is citric acid.
There is 0.0342 moles of NaOH consumed.
Explanation:
Step 1: Data given
Mass of the unknown acid = 2.19 gram
Titrating with 0.560 M of NaOH
The equivalence point is reached when 61.0 mL are added
Molar mass of oxalic acid = 90.03 g/mol
Molar mass of citric acid = 192.12 g/mol
Step 2: The balanced equations for both acids
The reaction between oxalic acid and NaOH is:
H2C2O4 + 2NaOH → Na2C2O4 + 2H2O
The reaction between citric acid and NaOH is:
H3C6H5O7 +3NaOH → Na3C6H5O7 + 3 H2O
Step 3: Calculate the number of moles of the acid
Moles = mass / Molar mass
In case of oxalic acid: 2.19 grams / 90.03 g/mol = 0.0243 moles
In case of citric acid: 2.19 grams /192.12 g/mol = 0.0114 moles
Step 4: Calculate number of moles of NaOH
The mole of NaOH required for titration;
number of moles = Molar mass * volume = (0.560 M * 0.061 L) = 0.03416 mol
Step 5: Calculate which acid
For each mole of oxalic 2 moles of NaOH is required, for 0.0243 mol citric acid 0.0243 *2= 0.0486 mol NaOH is required. This is more than the number of moles consumed.
For each mole of citric acid 3 moles of NaOH is required, for 0.0114 mol citric acid 0.0114 * 3= 0.0342 mol NaOH is required. This is the number of moles NaOH used for the titration.
The unknown acid is citric acid. There is 0.0342 moles of NaOH consumed.
