(^66) Aptitude Test Problems in Physics
(i.e. a direct transition from the solid to
the gaseous state) of water at the triple
point.
2.33. The saturated vapour pressure above
an aqueous solution of sugar is known to be
lower than that above pure water, where
it is equal to psat, by Op = 0.05psatc,
Fig. 66
where c is the molar concentration of the
solution. A cylindrical vessel filled to
height h^1 =10 cm with a sugar solution of
concentration c 1 = 2 x 10-3 is placed un-
der a wide bell. The same solution of con-
centration c^2 = 10-3 is poured under the
bell to a level h 2 < h 1 (Fig. 66).
Determine the level h of the solution in
the cylinder after the equilibrium has been
set in. The temperature is maintained con-
stant and equal to 20 °C. The vapour above
the surface of the solution contains only
water molecules, and the molar mass of
water vapour is .t = 18 X 10-3 kg/mol.
2.34. A long vertical brick duct is filled
with cast iron. The lower end of the duct
is maintained at a temperature T 1 >
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