Question

В четырехсклянках без этикеток находятся следующие вещества: формалин, водный раствор этилена, этанол, циклогексан. Как химическим путем распознать, какое вещество находится в каждой из склянок? Запишите уравнения соответствующих реакций.

Answer 1

К формалину добавить аминокислоту, получится желтая окраска: HCOH + NH2-CH2-COOH -> H2O + HC=N-CH2-COOH
Этилен обесцвечивает бромную воду; C2H4+Br2 = C2H4Br
Этанол окисляют проволокой оксида меди, в результате на ней образуется альдегид чистая медь: Сн3 - СН2 - ОН + СuO =CH3 - COH + Cu + H2O.
Ну а циклогескан просто остался лишним =)

Answer 2

Identifying the Substances in the Four Bottles

To identify the substances in each of the four bottles, we can use chemical reactions specific to each substance. By observing the reactions, we can determine the identity of the substances. Let's go through each substance and the corresponding reaction:

1. Formaldehyde (Formalin): - Formaldehyde can be identified by its reaction with silver nitrate (AgNO3) to form a white precipitate of silver mirror. - The reaction equation is as follows: ``` CH2O + 2AgNO3 + 3OH- → Ag2O + 2HCO3- + 2H2O ``` - The formation of a silver mirror confirms the presence of formaldehyde.

2. Ethylene Glycol (Water Solution of Ethylene Glycol): - Ethylene glycol can be identified by its reaction with potassium permanganate (KMnO4) in the presence of sulfuric acid (H2SO4) to form a colorless solution. - The reaction equation is as follows: ``` C2H6O2 + 2KMnO4 + 3H2SO4 → 2MnSO4 + 2K2SO4 + 2H2O + 2CO2 ``` - The formation of a colorless solution confirms the presence of ethylene glycol.

3. Ethanol: - Ethanol can be identified by its reaction with potassium dichromate (K2Cr2O7) in the presence of sulfuric acid (H2SO4) to form a green solution. - The reaction equation is as follows: ``` C2H5OH + K2Cr2O7 + H2SO4 → Cr2(SO4)3 + K2SO4 + CH3COOH + H2O ``` - The formation of a green solution confirms the presence of ethanol.

4. Cyclohexane: - Cyclohexane can be identified by its reaction with bromine (Br2) to form a colorless solution. - The reaction equation is as follows: ``` C6H12 + 3Br2 → 6HBr ``` - The disappearance of the red-brown color of bromine confirms the presence of cyclohexane.

Please note that these reactions are specific to the mentioned substances and can be used to identify them in the absence of labels on the bottles.