Saved Bookmarks
| 1. |
A volume occupied by a saturated vapour is reduced isothermally n-fold. Find what fraction eta of the final volume is occupied by the liquid phase if the specific volumes of the saturated vapour and the liquid phase differ by N times (N gt n). Solve the same problem under the condition that the final volume of the substance corresponds to the midpoint of a horizontal portion of the isothermal line in the diagram p, V. |
|
Answer» Solution :We let `V'_l` = specific volume of liquid. `V'_v = N V'_l` = specific volume of vapour. Let `V` = original volume of the vapour. Then `M (PV)/(RT) = m_l + m_v (V)/(N V'_l)` or `(V)/(n) = (m_l + N m_v) V'_l` So `(N - 1)m_l V'_l = V (1 - (1)/(n)) = (V)/(n)(n - 1)` or `eta = (m_l V'_l)/(V//n) =(n-1)/(N - 1)` In the case when the final volume of the substance CORRESPONDS to the midpoint of a HORIZONTAL portion of the isothermal LINE in the `p, v` diagram, the final volume must be `(1 + N)(V'_l)/(2)` per unit mass of the substance. Of this the volume of the liquid is `V'_1//2` per unit total mass of the substance. Thus `eta = (1)/(1 + N)`. |
|