Text b our practical classes
In the chemical laboratory
Now we are in the chemical laboratory. There are some rules for everybody working here. A white gown and a cap are necessary. We also keep vessels used for experiment absolutely clean, register all the phenomena observed. Any particular reaction must be conducted under strictly definite conditions, otherwise the result of the reaction will be unreliable. We carefully follow all these instructions.
Our practical classes
consist of theoretical, practical and laboratory work. During the
theoretical part junior students discuss the main questions with
their teacher. Only after that they can prove the equations with the
help of reactions.
In our chemical laboratories we carry out different experiments and observe many reactions. I’d like to give examples of oxidation-reduction reactions. There are three types of them: intermolecular, intramolecular and disproportional reactions. The first type is characterised by a change in the oxidation state of the atoms in different molecules. In case of intramolecular reactions we take into account a change in the oxidation state of different atoms in one molecule, for instance:
2Cu(NO3)2 = 2CuO + 4NO2 + O2
2KClO3 = 2KCl + 3O2
The third type is represented by the reactions in which the oxidation state of atoms of the same element simultaneously changes in both directions.
You can come and carry out experiments together with the students of my group. You are welcome any time.
NOTES:
to observe [o zə:v] наблюдать
particular [pa: tikjulə] отдельный
to conduct [kəndΛ kt] выполнять, проводить
under strictly в строго определённых
definite conditions условиях
otherwise [ Λðə waiz] иначе
unreliable [Λnri laibl] ненадёжный, неточный
to follow [fol əu] следовать
to consist of... [kon sist] состоять из ...
an equation [i kweiζ n] уравнение
simultaneously [ simjul teinə sli] одновременно
Ex. 9. Speak on the following points:
1. In the Chemical Laboratory
2. Laboratories of Our Academy
3. My Practical Classes In the Chemical Laboratory,
using information of the two texts.
Supplementary vocabulary
Chemical substances
oxides
acids
bases
salts
Processes and types of chemical reactions
acidification - подкисление, ацидификация
carbonation - карбонизация
causticization - каустификация
denitration - денитрация
elutriation - отмучивание
hydrolysis - гидролиз
oxidation - окисление
resorption - резорбция
interaction - взаимодействие
evolution - выделение
reversible/irreversible reaction – обратимая/необратимая реакция
Properties of chemical substances
absorptivity - поглощаемость
alkalinity - щёлочность
basicity - основность
brittleness - ломкость, хрупкость
colour - цвет
conductivity - электропроводность
fragility - хрупкость
malleability - ковкость
overacidity - надкислотность
plasticity - платичность
solubility - растворимость
transparency - прозрачность
Equipment
automatic balance – весы с автоматическим накладыванием гирь
automatic burette - бюретка с автоматической установкой
balance needle - стрелка весов
balance pan - чашка весов
beam balance - рычажные весы
bottle - бутылка, склянка
bowl - чаша, чашка
bulb pipette - пипетка с шаровым расширением
Bunsen burner - бунзеновская горелка
filter - фильтр
gas thermometer - газовый термометр
stand - штатив
test-tube clamp - держатель для пробирок
test-tube stand - штатив для пробирок
vial - пузырёк