Unknown liquids practical
Provided in lab
Waterbaths (shared): 37 °C 100 °C
50 cm3 boiling tubes + rack
waterproof marker pen
timer
Benedict's solution
Procedure
1) Label 6 tubes (A-F) and put your name or mark on them. Place them in order in the rack. Prepare a table for results.
2) Measure 2.5 cm3 of glucose solution into tube A.
3) Measure 2.5 cm3 of liquid X into tubes B, D and E.
4) Measure 2.5 cm3 of liquid Y into tubes C and F.
5) Transfer tubes E and F to the 100 °C waterbath. Note the time, so as to leave them for 15 minutes.
6) Perform Benedict's test on tubes A, B and C, and replace them in the rack. Record the results in a table.
7) Allow the tubes E and F to cool in the rack.
8) Add 2.5 cm3 of liquid Y to the contents of tube D. Shake to mix, then place the tube in the 37 °C waterbath. Note the time, so as to leave it for 15 minutes.
9) Similarly, add 2.5 cm3 of liquid Y to the contents of tube E, and add 2.5 cm3 of liquid X to the contents of tube F. Shake each tube to mix, then place it in the 37 °C waterbath. Note the time, so as to leave it for 15 minutes.
10) Perform Benedict's test on tubes D, E and F, and replace them in the rack.
11) You may perform any other tests on solutions X and Y if you like
12) Record the results in the table. Complete your report and interpretation, explaining the significance of each stage in the procedure. Hand it in before leaving the laboratory.
Click the camera icon to see a photo of results for this experiment.
