Лаборатория иши №5

First aid

1. 
   In case of chemical burns, the burnt area should be thoroughly washed with a stream of cold water, wiped with alcohol, in case of heat burns, wiped thoroughly with alcohol and consult a doctor.
   
2. 
   In case of chemical damage to the eye, rinse thoroughly with cold water and consult a doctor.
   
3. 
   In case of contact with eyes, seek medical advice immediately.
   
4. 
   In case of chemical poisoning, the patient should be taken to fresh air, vomited, and given artificial respiration if necessary.
   
5. 
   When working with toxic substances, the pharmacy must have antidote.
   

LABORATORY WORK №1

Absorption of hydrogen chloride, production of hydrochloric acid
Purpose of work:Study of the process of absorption of hydrochloric acid from hydrochloric acid under the action of sulfuric acid.

Theoretical information

Before covering the topic, let’s talk about the distribution of chlorine, the main product of hydrogen chloride extraction. In nature, chlorine is freely found only in volcanic gases. Its compounds are common. The most important of them are: sodium chloride (NaCl), potassium chloride (KCl), magnesium chloride MgCl2 * 6H2O, sylvinite (composed of KCl with NaCl, carnalite KCl * MgCl2 * 6H2O, kainite MgSO4 * KCl * 3H2O. in ocean, sea, lake waters, and in small amounts in animal and plant organisms. Chlorine and crust make up 0.05% of the mass.
Chlorine is a yellowish-green, poisonous gas with a pungent odor. 2.5 times heavier than air. At 20o C, 2.3 volumes of chlorine are soluble in 1 volume of water. Chlorine inflames the airways, suffocating with large amounts of chlorine can be fatal. A solution of chlorine in water is called chlorinated water.
Chlorine reacts specifically with hydrogen. When mixed with chlorine and hydrogen in the dark, it does not react. But when strongly illuminated, the reaction occurs very rapidly, with an explosion:
Cl2 + H2 = 2HCl
Tests show that this reaction goes much more complicated. The Cl2 molecule absorbs the light quantum hv and the atoms separate. Under the influence of a quantum of light, the initial excitation sequence forms a chain of reactions in which it occurs. Such reactions are called chain reactions. Hydrogen chloride is obtained by the chain reaction of chlorine with hydrogen. NNSemyonov found that chain reactions are very common and that free atoms or groups of atoms - radicals - are formed and then they interact. Such reactions play a major role in most chemical processes (combustion, explosion, polymerization, etc.).
Hydrogen chloride is one of the most important compounds of chlorine. It is a colorless gas with a pungent odor. Inflammation and suffocation of the respiratory tract when inhaled with it. 1.3 times heavier than air. It "catches" in humid air, that is, it combines with water vapor in the air to form small mist droplets. At 0 ° C, about 500 volumes of hydrogen chloride are soluble in one volume of water. A solution of hydrogen chloride in water is called hydrochloric acid.
Chlorine is used to disinfect drinking water (chlorination of water), bleach fabrics and papers. Much of it is used to make hydrochloric acid, chlorinated lime, as well as various chemical compounds containing chlorine. The method based on the interaction of hydrogen chloride sodium chloride with concentrated sulfuric acid in the laboratory is called sulfate, the method based on the combustion of hydrogen in chlorine is called synthetic.
Absorption of hydrogen chloride in water is a process that occurs with the rise in temperature of the resulting hydrochloric acid. As the temperature rises, the vapor pressure on the surface of hydrochloric acid also increases.
When the vapor pressure of hydrogen chloride and water vapor is equal to atmospheric pressure, the acid boils and the evaporation of water reaches a high level. Under adiabatic conditions, the heat required for water to evaporate is replenished by the heat of liquefaction of HCl, while the acid concentration increases continuously. The temperature of the boiling acid first rises to 1100C and the concentration reaches 20.24% (pressure 101325 N / m2 or 760 mm Hg), then decreases. The acid, which contains 20.24% HCl, is a constantly boiling mixture of HCl and H2O.
If the partial pressure of HCl in the gas phase always exceeds the pressure of HCl on (the surface) of the boiling mixture, the acid concentration reaches 20.24% and continues to increase, while the boiling temperature decreases. Therefore, an increase in the amount of HCl gas leads to an increase in the acid concentration under adiabatic conditions.
When hydrogen chloride is added to boiling water, the gas leaving the absorber initially consists of water vapor, but as the acid concentration increases, the amount of HCl gas in the exhaust gas also increases. Therefore, when concentrated acid is obtained in a single absorber, some hydrogen chloride is not absorbed.
For complete absorption of HCl, it is advisable to send the gas through several absorbers opposite to the water, or to use absorbers with plates, nozzles inside. Only then will the gas leaving the absorbers consist only of water vapor.