Solution and solvation

Solution is a homogeneous mixture of a liquid (the solvent) with a gas or solid (the solute). In a solution, the molecules of the solute are discrete and mixed with the molecules of solvent. There is usually some interaction between the solvent and solute molecules . Two liquids that can mix on the molecular level are said to be miscible. In this case, the solvent is the major component and the solute the minor component.

Hydrolysis is a chemical reaction of a compound with water. For instance, salts of weak acids or bases hydrolyse in aqueous solution, as in

NaCH₃COO + H₂O = Na⁺ + OH^- + CH₃COOH

The reverse reaction of esterification is another example.

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Solvation is the interaction of ions of a solute (the substance dissolved in a solvent in forming a solution) with the molecules of solvent. For instance, when sodium chloride is dissolved in water the sodium ions attract polar water molecules, with the negative oxygen atoms pointing towards the positive Na⁺ ion. Solvation of transition-metal ions can also occur by formation of coordinate bonds, as in the hexaquocopper (II) ion (Cu(H₂O)₆]²⁺. Solvation is the process that causes ionic solids to dissolve, because the energy released compensates for the energy necessary to break down the crystal lattice. It occurs only with polar solvents. Solvation in which the solvent is water is called hydration. Solvay process (ammonia-soda process) is an industrial method of making sodium carbonate from calcium carbonate and sodium chloride. The calcium carbonate is first heated to give calcium oxide and carbon dioxide, which is bubbled into a solution of sodium chloride in ammonia. Sodium hydrogencarbonate is precipitated.

The sodium hydrogencarbonate is heated to give sodium carbonate and carbon dioxide. The ammonium chloride is heated with calcium oxide (from the first stage) to regenerate the ammonia. The process was patented in 1861 by the Belgian chemist Ernest Solvay (1838-1922).

Lesson 4 Part 1 How to Translate “to follow” and its derivatives

“To follow” has a few meanings - следовать за, следить за, использовать, прослеживаться. “Following” - следующий за, использующий (-ся), после. “Followed by” - за которым следует, с последующим. E.g.: We followed this method. - Мы следовали этому методу. Following the experiment the end product was tested. - После эксперимента конечный продукт был протестирован.

Vocabulary

curve - кривая

formation - образование

procedure - методика

interdiffusion - взаимная диффузия

X-ray - рентгеновский луч

Practice

Translate the following sentences paying attention to the verb “to follow”.

1. This usage is not followed in carbohydrate chemistry.

2. Then followed the discovery of a new compound.

3. The reaction is followed by temperature rise.

4. The condensation is followed by a rapid epoxide formation.

5. This apparatus was followed by us to determine the concentration of the acid.

6. One of the procedures described in Part 1 has been followed here.

7. Identical procedures are followed in preparing this solution.

8. The opening of the epoxide ring is not followed by the displacement of bromine by oxygen.

9. It is to be noted that according to the classical ideas the reaction under consideration would be expected to follow the complete path of potential energy curve.

10. To reach the results we followed this method.

11. Following the measurements we were able to determine the mass of the substance.

12. This issue is considered in Chapter 9 followed by Chapter 10.

13. Molecular layers of different substances may be deposited above one another, and their interdiffusion might be followed with the help of X-ray.

14. The reactions were too rapid to be followed by other method.

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