Little chemist

The little chemist was such a game with chemistry for inquisitive students. In the 60s of the last century, in stores with ambitious toys, you could buy a set of a little chemist. The kit included test tubes and various reagents and a simple instruction on what to mix with what and how to understand what is being observed.

The analysis is divided into:

• qualitative - answers the question what is in the tube
• quantitative - answers the question of how much of something is in the tube.

The analysis requires rational work because:

• small amounts may not be detected,
• contamination with other compounds may mask the effects of simple reactions,
• the sample may have been badly taken.

When there is a low concentration of something, the test solution is concentrated in such a way as not to destroy what we are looking for.

The little chemist taught that:

1. mercury ions Hg +2 floating in the polluted water give a white precipitate with a drop of sulfuric acid solution.
2. mercury ions Hg + 2 floating in polluted water with a droplet of hydrogen sulfuric acid solution black sludge soluble only in contrast to other deposits in hot nitric acid or aqua regia.
3. Hg + 2 mercury ions floating in polluted water with a droplet of potassium iodide solution give a green precipitate.

Etc.

A drop of cobalt nitrate and ammonium thionate may be added to the concentrated dry water sample (after evaporation), blue crystals will appear. It is a sensitive reaction capable of detecting 1 mercury in 25,000 water molecules.

In addition, the evaporation residue of mercury-contaminated test water dissolved in nitric acid solution dropped onto a copper plate or a copper coin will, over time, give rise to a gray metallic mercury stain. After washing with water and wiping dry, the copper plate or coin will take on a normal shine.

It took the little chemist an hour to complete these tests. Today, analysis using spectral-emission methods takes a fraction of a second. It allows you to detect what the eye and glasses of many wise men from a company limousine cannot see.