Q. Explain Lane Eynon Method procedure?
You will be carrying out the procedure in two steps using Lane Eynon Method.
Step 1
It involves the standardization of copper sulphate solution. The procedure for this standardization can be conducted in the underlined manner as:
1) Pipette accurately 5 ml of Solution A and Solution B in conical flask of 250 ml capacity.
2) Heat this mixture to boiling on an asbestos gauge and add standard invert sugar solution from the burette about 1ml less than the expected volume which will reduce the Fehling solution of say, 48 ml.
3) Add 1 ml methylene blue indicator.
4) Carry out the titration and complete it within 3 minutes.
5) The change in blue to reddish brown colour due to cuprous oxide formation is taken as the end point.
6) From the volume of the invert sugar solution used, the strength of CuSO4 is calculated by multiplying the titrated value with 0.001 (mg/ml of the standard invert sugar solution). This is known as Fehling factor.
Note: Carry out the titration till you get consecutive titre value. This means you may have to repeat the titration 3-4 times till you get the same result.
Step 2
It involves the titration of the sample honey solution wherein the steps can be followed as given below:
1) Place accurately 1 gm of honey solution in 250 ml of volumetric flask.
2) Dilute with about 150 ml of water.
3) Mix thoroughly contents of glass and make the volume to 250 ml.
4) In another conical flask, add 5 ml of Fehling A + 5 ml of Fehling B.
5) Heat to boiling with 20 ml of water.
6) From burette add honey solution (approx 40 ml) and boil.
7) Add methylene blue indicator do the titration within 3 minutes.
8) Carry out the titration till blue colour changes to red.