THEORY:
Oxidation half reaction of oxalic acid is
C₂O4 — – 2e ——-> 2CO₂
1 mol 2 mol
Therefore, Eq. wt. of oxalic acid = mol. wt./ 2 = wt. of H₂C₂O4. 2H₂O / 2 =126/2 =63.0
By the definition of a normal solution,
1000 ml of (N) oxalic acid = 63.0 gm
100 ml of N / 10 oxalic acid = 6.3 gm
or 100 ml of N / 10 oxalic acid = 0.63 gm
APPARATUS :
1) 100 ml measuring flask
2) Watch glass
3) Funnel
4) Pipette
CHEMICALS:
Oxalic acid crystals.
PROCEDURE :
i) Accurately weigh out about 0.63 gm of pure oxalic acid crystals on a watch glass.
ii) Transfer it quantitatively into a clean 100 ml measuring flask with the help of a funnel. Wash down all the adhering particles with some distilled water, and finally make the volume up to the mark by the addition of more distilled water. Stopper the flask, and shake well to make it homogeneous.
RESULTS:
Wt. of oxalic acid crystals taken = 0.66 (say)
Calculation of ‘factor’:
0.63 gm oxalic acid in 100 ml makes the solution N /10
Therefore, 0.66 gm oxalic acid in 100 ml makes the solution 0.66 /0.63 xN/10 =N/10 (f = 1.048).