Help please. Steps and proper labeling Answe for b is 169 J Answe for b is 169 J
ID: 1769681 • Letter: H
Question
Help please. Steps and proper labeling Answe for b is 169 JAnswe for b is 169 J
In the diagram below, the lower half of a container is occupied by water at 25° C, and the upper half is initially vacuum. The volume of the evacuated region is 3.00L. The two halves are separated by a partition. The entire containter is immersed in a thermal reservoir, also at 25 C The equilibrium vapor pressure at this temperature is 3.169 kPa (wikipedia). When the partition is removed, (a) What mass of liquid water evaporates? (Neglect the change in the volume occupied by the liquid phase.) (b) How much heat flows from the thermal reservoir into the container (in order to maintairn constant temperature?) vacuum V-3.00L
Explanation / Answer
when the partition is removed water will evaporate to fill the empty space until it reaches the equilibrium position.
volume of the vapor V = 3.0 L = 3.0e-3 cu.m
vapor pressure P = 3.169 kPa
temperature T = 25 C = 278 K
PV = nRT
n = PV/RT = 3.0e-3 *3.169e+3 /(8.31 *278) = 0.00412 mol
1 mol of water = 18 g
mass of water vaporised = 0.00412*18 = 0.0742 g
L-heat of vaporization = 2.25e+6 J/kg
heat required to evaporate = 0.0742e-3 *2.25e+6 = 166.87 J
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