ION DETECTIVE MYSTERY: CASE OF THE HIDDEN PHOSPHATE

Ajouté : 2026-06-05

[00:00:01]Today, detectives, we have an unknown white salt. Your mission, identify the anion.

[00:00:05]>> Let's start testing right away.

[00:00:07]>> But sir, how do we even begin?

[00:00:08]>> We follow the systematic analysis step by step, no guessing. First, the preliminary examination.

[00:00:13]Let me add some salt in test tube.

[00:00:16]Now, I add distilled water into it. It's insoluble in water. Insoluble confirms carbonate or phosphate. Add salt into the test tube. Adding concentrated H2SO4 using dropper. Heating the mixture. No vinegar smell. No smell. Acetate, CH3COO- absent. No colored fumes, either. No bromide, result negative. No nitrate, result negative.

[00:00:42]No iodide, result negative.

[00:00:45]>> We're getting closer.

[00:00:47]No pungent smell of HCL.

[00:00:49]No chloride, Cl- ion. Group two eliminated. Group two test, salt plus concentrated H2O4 plus heat. No smell, no fumes, group two absent. Let's detect the final group three. Take salt into the test tube.

[00:01:01]>> Add HCL. Add barium chloride into the test tube. White precipitates form.

[00:01:05]>> White solid could be barium sulfate or barium phosphate. Excess HCL into the white precipitates. White precipitates dissolved. White precipitates dissolve in HCL, eek, phosphate ion.

[00:01:19]Adds AgNO3 into the salt. Yellow precipitates, eek, phosphate confirmed.

[00:01:25]PO43- + 3 AgNO3 yields Ag3PO4, a yellow precipitate, + 3 NO3.

[00:01:31]Case solved. Excellent teamwork, detectives. Science is all about elimination and proof. We used the group test. Then the confirmatory test with silver nitrate.

[00:01:41]>> Phosphate confirmed.