Preparation of the Test Tubes:

1. Label 4 clean test tubes "1" through "4" and place them in a test tube rack.
2. Label the disposable pipets to prevent contamination of the solutions.
3. Add 4 to 5 drops of KH2PO4, Na2SO4, NaCl, and NaNO3 to the test tubes in the order shown in table 2.
4. Add 5 M ammonia to each solution drop by drop until it is basic when tested with litmus paper. After mixing, touch the solution in the test tube with a clean stirring rod and then touch the litmus paper with the stirring rod for testing.
5. In a fifth test tube, add 10-15 drops of the unknown solution. Then add 5 M ammonia by drops until it is basic when tested with litmus paper. After mixing, touch the solution in the test tube with a clean stirring rod and then touch the litmus paper with the stirring rod for testing.

Table 2: Solutions for Step 1