Ex. 2. Pay attention to the structure оГ the following words. Translate
them into Russian:
a) somebody, someone, something, somewhere, somehow, somewhat,
sometime, sometimes
b) important, pleasant, abundant, resistant, brilliant, disinfectant,
lubricant, significant
c) freedom, kingdom, wisdom
Ex. 3. Define the
meanings оГ the word point in the following scntcnccs:
1.
Point A on the graph corresponds to the boiling
point of a solution.
2. The reaction goes to completion when the temperature is kept in the range
of25-30°C, this is a particularly important
point. 3. At this
point he stopped
for a minute and then continued his explanation. 4. There arc different
points
of view concerning the hypothesis. 5. The
inchingpoint of crystalline iodine
is 114°C. 6. The proccss of melting can be described from the molccular
viewpoint. 7. Up to this
point everything was all right, but then something
happened and the proccss became unstable. 8. It must be
pointed out that
only a crystal is characterized by regular anangemcnt of atoms and molcculcs.
9. It is a very
interesting point, wc shall discuss it later.
Ex. 4. Find the predicate and the subject in the following sentences:
1. That the properties of liquid iodine and solid iodine arc different is
quite obvious. 2. That the density o f a liquid is less than that of a
corresponding crystal can be easily explained. 3. How wc are to make
measurements will be dear from the instruction. 4. Whether high pressure
is ncccssary is to be known from the articlc.
Text 18 A
The Nature of a Liquid
When iodine crystals arc heated to U4°C, they melt forming liquid
iodine. The temperature at which the crystals and the liquid arc in
equilibrium — that is, at which crystals have no tendency to melt or the
liquid has no tcndcncy to freeze— is callcd the
melting point of the crystals,
and the freezing point of the liquid. This temperature is I I4°C for iodine.
Liquid iodine differs from solid iodine (crystals) mainly in its fluidity.
Like the solid, and unlike the gas, it has a definite volume (1 g occupics
about 0.2 cm’), but it docs not have a definite shape: instead, it fits itself to
the shape of the bottom part of its container.
From the molccular viewpoint the proccss of melting can be described
in the following way. As a crystal is heated, its molcculcs arc increasingly
agitated, and move about more and more vigorously, but at lower
temperature, this thermal agitation docs not carry any one molecule any
significant distance away from the position fixed for it by the arrangement
of its neighbours in the crystal. At the melting point the agitation finally
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bccomcs so great that it causcs the molcculcs to slip by one another and to
change somewhat their location relative to one anothcr. Thcy continue to
stay close together, but do not continue to retain a regular fixed arrangement.
Instead, the grouping o f molcculcs around a given molcculc changcs
continually, sometimes being much like the close packing of the crystal,
in which cach iodine molcculc has twelve near neighbours, and sometimes
considerably different, the molcculc has only ten or nine or eight near
neighbours. Thus, a liquid, like a crystal, is a condensed phase, as contrasted
with a gas, the molcculcs being piled rather closcly together; but whereas
a crystal is characterized by regularity of atomic or molccular arrangement,
a liquid is characterized by randomness of structure. The randomness of
structure is usually the reason why the density o f a liquid is somewhat less
than that of the corresponding crystal.
W ords an d W o rd -C o m b in atio n s to Be M em orized
away, bottom, characterize, considerably, container, contrast, differ from,
differ in, distance, finally, fit, fix, freeze, increasingly, instead, mainly, melt,
melting point, phase point, melting, random, regular, relative, shape, significant,
sometimes, somewhat, stay, that is, thermal, viewpoint
Ex. 5. Give the Russian equivalents for the following:
be in equilibrium, the tcndcncy for crystals to melt, freeze the liquid,
differ in properties, unlike the liquid, have a definite volume, instead, fit
itself to the shape of, in the following way, carry away, changc somewhat,
stay elose together, the elose packing of the crystal, considerably different,
a randqm structure, the density of a liquid
Ex. 6. Give the English equivalents for the following:
naipcTb до, точка плавления вещества, отличаться от, иметь опре
деленную форму сосуда, с точки зрения, изменить местоположение,
ipynmtpoBKa молекул вокруг, ближний соссд, плотная упаковка, ха
рактеризоваться чем-л., произвольное расположение молекул, не
сколько меньше, каждая молекула йода, относительно друг друга,
отличаться чем-л., в отличие
от газа
Ex. 7. Fill in the blanks with prepositons where ncccssary.
1. Crystals ... iodine melt when they arc heated ... I14°C. 2. Liquid
iodine differs ... solid iodine... its fluidity. 3. Usually, liquid fits itself...
the shape... the bottom spacc ... its container. 4. The proccss... melting
can be described... the following way. S. This proccss is intcrcsing... the
molccular viewpoint. 6. Regularity... atomic or molccular arrangement is
characteristic ... a crystal. 7. A liquid is characterized ... randomness ...
structure. 8. A solid occupics ... a definite volume.
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