Metods:

Add four drops of the red phenol solution to the urea solution (firts, put two drops of urea on a microscope slide to the next experiment).

Add 1 drop of NaOH.

Add acetic acid slowly untill the pink color disapear.

Add the soy flour, mix and wait a few minutes.

Write down the observed results.

Experiment 2 : Urea oxalate

Material:

2 drops of urea 0.1 M

1 drop of oxalic acid 0.5 M

2 microscope slides

Metods:

Put two drops of urea on each slide

Add a drop of oxalic acid on one of the slides (make sure you know latter wich one has the oxalic acid)

Wait aa few minutes

Examine the blades by naked eye and, if it's possible, on a microscope.

Objectives:

To identify the effect of each of the reagents used (pH changes for example).

To characterize the urea and the urease.