DRAFT: This module has unpublished changes.

Sample Calculation: The analysis of a sea water sample


Step

Action

Observation

Possible Explanations

1

Added Ba(NO3)2 solution by drops until precipitation occurs.

White precipitate formed.

Possibly SO42- and PO43- are present.

2

Separated the precipitate from the supernatant. Added

HNO3 solution to the precipitate.

Some precipitate dissolved.

The remaining precipitate is BaSO4, indicating the presece of SO42-.

3

Separated the precipitate from the supernatant. Added

AgNO3 to the supernatant.

Yellow precipitate formed.

The precipitate is Ag3PO4, which confirms the presence of PO43-.

4

Added AgNO3 solution to the supernatant from step 2, and

then added NH3 solution.

White precipitate formed. Adding NH3 solution dissolved the precipitate.

The precipitate that dissolves in NH3 is AgCl, indicating the presence of Cl-.

5

Tested for NO3-.

No change.

NO3- can be excluded.


The analysis confirmed the presence of Cl-, SO42-, and PO43- ions.

DRAFT: This module has unpublished changes.