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Condition |
free/or 0.5$ |
| 581 | Find the mass of all molecules leaving one square centimetre of water surface per second into a saturated water vapour above it at a temperature t = 100 °C. It is assumed that n = 3.6% of all water vapour molecules falling on the water surface are retained in the liquid phase. |
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| 582 | Find the pressure of saturated tungsten vapour at a temperature T = 2000 K if a tungsten filament is known to lose a mass n= 1.2·10^(-13) g/(s•cm2) from a unit area per unit time when evaporating into high vacuum at this temperature. |
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| 583 | By what magnitude would the pressure exerted by water on the walls of the vessel have increased if the intermolecular attraction forces had vanished? |
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| 584 | Find the internal pressure pi of a liquid if its density ρ and specific latent heat of vaporization q are known. The heat q is assumed to be equal to the work performed against the forces of the internal pressure, and the liquid obeys the Van der Waals equation. Calculate pi in water. |
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| 585 | Demonstrate that Eqs. (2.6a) and (2.6b) are valid for a substance, obeying the Van der Waals equation, in critical state. Instruction. Make use of the fact that the critical state corresponds to the point of inflection in the isothermal curve p(V). |
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| 586 | Calculate the Van der Waals constants for carbon dioxide if its critical temperature Tcr = 304 K and critical pressure pcr = 73 atm. |
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| 587 | Find the specific volume of benzene (C6H6) in critical state if its critical temperature Tcr = 562 K and critical pressure pcr = 47 atm. |
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| 588 | Write the Van der Waals equation via the reduced parameters π, ν, and τ, having taken the corresponding critical values for the units of pressure, volume, and temperature. Using the equation obtained, find how many times the gas temperature exceeds its critical temperature if the gas pressure is 12 times as high as critical pressure, and the volume of gas is equal to half the critical volume. |
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| 589 | Knowing the Van der Waals constants, find: (a) the maximum volume which water of mass m = 1.00 kg can occupy in liquid state; (b) the maximum pressure of the saturated water vapour. |
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| 590 | Calculate the temperature and density of carbon dioxide in critical state, assuming the gas to be a Van der Waals one. |
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| 591 | What fraction of the volume of a vessel must liquid ether occupy at room temperature in order to pass into critical state when critical temperature is reached? Ether has Tcr = 467 K, pcr =35.5 atm, M = 74 g/mol. |
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| 592 | Demonstrate that the straight line 1-5 corresponding to the isothermal-isobaric phase transition cuts the Van der Waals isotherm so that areas I and II are equal (Fig. 2.5). |
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| 593 | What fraction of water supercooled down to the temperature t = —20 °C under standard pressure turns into ice when the system passes into the equilibrium state? At what temperature of the supercooled water does it turn into ice completely? |
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| 594 | Find the increment of the ice melting temperature in the vicinity of 0 °C when the pressure is increased by dp = 1.00 atm. The specific volume of ice exceeds that of water by dV' = 0.091 cm3/g. |
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| 595 | Find the specific volume of saturated water vapour under standard pressure if a decrease of pressure by dp = 3.2 kPa is known to decrease the water boiling temperature by dT = 0.9 K. |
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| 596 | Assuming the saturated water vapour to be ideal, find its pressure at the temperature 101.1 °C. |
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| 597 | A small amount of water and its saturated vapour are enclosed in a vessel at a temperature t = 100 °C. How much (in per cent) will the mass of the saturated vapour increase if the temperature of the system goes up by dT = 1.5 K? Assume that the vapour is an ideal gas and the specific volume of water is negligible as compared to that of vapour. |
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| 598 | Find the pressure of saturated vapour as a function of temperature p(T) if at a temperature T0 its pressure equals p0. Assume that: the specific latent heat of vaporization q is independent of T, the specific volume of liquid is negligible as compared to that of vapour, saturated vapour obeys the equation of state for an ideal gas. Investigate under what conditions these assumptions are permissible. |
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| 599 | An ice which was initially under standard conditions was compressed up to the pressure p = 640 atm. Assuming the lowering of the ice melting temperature to be a linear function of pressure under the given conditions, find what fraction of the ice melted. The specific volume of water is less than that of ice by dV' = 0.09 cm3/g. |
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| 600 | In the vicinity of the triple point the saturated vapour pressure p of carbon dioxide depends on temperature T as log p = a — b/T, where a and b are constants. If p is expressed in atmospheres, then for the sublimation process a = 9.05 and b = 1.80 kK, and for the vaporization process a = 6.78 and b = 1.31 kK. Find: (a) temperature and pressure at the triple point; (b) the values of the specific latent heats of sublimation, vaporization, and melting in the vicinity of the triple point. |
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