3.Робота над текстом за професійним спрямуванням:

Завдання до тексту

Робота над текстом за професійним спрямуванням: ESTER

It has already been explained, that an ester is the product formed by the reversible reaction between an acid and an alcohol. If an acid and an alcohol are mixed a condition of equilibrium will eventually be setup when the rates of the direct reaction (esterification) and reverse reaction (hydrolysis) are equal. It follows from the law of mass action that an increase in the molecular concentration of anyone of the, re-acting substances will displace the equilibrium in the opposite direction. Any excess of water will diminish the proportion of ester present at equilibrium. Consequently, in the preparation of esters, it is necessary as a rule to use the anhydrous acid and alcohol in order to obtain good yields, and the reaction is usually carried out in the presence of an acid catalyst (concentrated sulphuric acid or dry hydrogen chloride).

An ester may be almost completely hydrolyzed if it is heat-ed with water, provided that a large enough proportion of water is used. The hydrolysis is usually slow, but is catalyzed by acids. It becomes complete if a dilute solution of an alkali is used instead of water, for the acid produced by hydrolysis is neutralized by the alkali as fast as it is formed, and so can take no further part in the reaction. Most esters of organic acids are pleasant — smelling, volatile liquids and many of them are used in perfumery and in the production of artificial flavouring agents.

Ethyl acatale is a typical example of an ester of an organic acid. It is formed when acetyl chloride or acetic anhydride acts on ethyl alcohol. Ethyl acetate is prepared by the interaction of alcohol and glacial acid in the presence of concentrated sulphuric acid.

Ethyl acetate is a colorless, mobile liquid, with a pleasant fruity odour. Its weight per ml is 0.9 and it boils at 77. It is soluble in water and is miscible with alcohol, ether and chloroform, forming neutral solutions. When ethyl acetate is boiled with water under reflux condensation, it slowly undergoes hydrolysis.

Answer the question:

1) What can you say about ester and its main features?

ЛІТЕРАТУРА: 1. Барановська Т.В. Граматика англійської мови. Збірник вправ: Навч. посібник. Видання друге, виправлене та доповненею – Мова англ., укр. – Київ: ТОВ “ВП Логос-М», 2007. – 384с.

2. Л.В. Мисик, А.Л. Арцишевська, Л.Р. Кузнєцова, Л.Л. Поплавська. Англійська мова. Комунікативний аспект. / За ред. доц. Мисик Л.В. – Підручник. – К.: Атіка, 2000. – 368с.

Практичне заняття № 3

Тема: Реклама і суспільство.

1. Read the texts and discuss the text

Advertisement

Although the average citizen is usually annoyed by all the advertisements printed in newspapers and magazines and the commercials broadcast on TV, the impact of the whole advertising industry on a single person is immense and plays a very important role in our lives. Advertising absorbs vast sums of money but it is useful to the community. What are the functions of advertisements? The first one to mention is to inform. A lot of the information people have about household devices, cars, building materials, electronic equipment, cosmetics, detergents and food is largely derived from the advertisements they read. Advertisements introduce them to new products or remind them of the existing ones. The second function is to sell. The products are shown from the best point of view and the potential buyer, on having entered the store, unconsciously chooses the advertised products. One buys this washing powder or this chewing gum, because the colorful TV commercials convince him of the best qualities of the product. Even cigarettes or sweets or alcohol are associated with the good values of human life such as joy, freedom, love and happiness, and just those associations make a person choose the advertised products. The aim of a good advertisement is to create a consumer demand to buy the advertised product or service. Children are good example as they usually want the particular kind of chocolate or toy or chewing-gum. Being naive they cannot evaluate objectively what is truthful and what is exaggerated and select the really good products unless they buy the goods and check for themselves. Thirdly, since the majority of advertisements are printed in our press we pay less for newspapers and magazines, also TV in most countries in cheap. The public advertising seen on street hoardings, railway stations and buildings makes people's life more joyful. Moreover, all those small ads in the press concerning "employment", "education" and "For sale and wanted" columns, help ordinary people to find a better job or a better employee, to sell or to buy their second-hand things and find services, or learn about educational facilities, social events such as, concerts, theatre plays, football matches, and to announce births, marriages and deaths. Thus despite our dissatisfaction when being bombarded by all the advertisers' information we must admit that they do perform a useful service to society, and advertisements are an essential part of our everyday life.