We offer the chemical tasks of enhanced difficulty for pupils of secondary/high schools

1. The hydrogen density of a mixture of methane, propane, oxygen and ozone is 18.4. Burning of 25 ml of this mixture produces 16 ml of a mixture of carbon dioxide with oxygen measured in the same conditions. The hydrogen density of this mixture increased to 19.75.
Calculate the parts by volume of the components of the initial gas mixture.
2. If one adds to the sodium carbonate solution the nitric acid solution at continuous stirring, 11.88 g of salt mixture can be extracted from the solution obtained. In contrary, if one changes the order of mixing the initial solutions, then 11.26 g of salt mixture can be extracted.
Calculate the masses of the substances in the initial solutions. (Please find two ways of finding the solution).
3. The mass part of nitrogen in the mixture

An interesting feature of silver water properties

The solution of the organic acid silver salt is suggested having relatively high solubility (= 1,800 mg/l). The above solution is stable to the scattered light action but under the influence of strong light, in particular, the sunlight produces a stable solution of colloid metal silver with pronounced opalescence.

Besides the known properties, the suggested silver salt solution is capable of fast healing the chemical and/or thermal burns. It is enough to treat 2–3 times during one evening the burn by the salt solution containing 50–100 mg per 1 liter of solution.

The suggested solution can be the object of thorough study/investigation.

All interested in an extensive investigation of the above properties and merits may obtain the silver water solution.

Contact phone (mobile): +38 066 9523460. Language of conversation – Russian.