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The boiling points for pure water and pure toluene are 100°C and 110.6°C respectively. Toluene and water are completely immiscible in each other. A well agitated equimolar mixture of toluene and water are prepared. If, at a total pressure of one standard atm. exerted by the vapours of water and toluene, the mole fraction of water X<sub>w</sub> in the vapour phase satisfies
A
[ <p><span>A. 0 w <p><span>B. X<sub>w</sub> = 0.5
B
0.5 w
C
X<sub>w</sub> = 1.0
Correct Answer:
0.5 w
The boiling points for pure water and pure toluene are 100°C and 110.6°C respectively. Toluene and water are completely immiscible in each other. A well agitated equimolar mixture of toluene and water are prepared. The temperature at which the above mixture will exert a pressure of one standard atm. is
A
Less than 100°C
B
100°C
C
Between 100 and 110°C
D
110.6°C
At 100°C, water and methylcyclohexane both have vapour pressures of 1 atm. Also at 100°C, the latent heats of vaporisation of these compounds are 40.63 kJ/mole for water and 31.55 kJ/mole for methylcyclohexane. The vapour pressure of water at 150°C is 4.69 atm. At 150°C, the vapour pressure of methylcyclohexane would be expected to be
A
Significantly less than 4.69 atm
B
Nearly equal to 4.69 atm
C
Significantly more than 4.69 atm
D
Indeterminate due to lack of data
In a wetted-wall tower, an air-H2S mixture is flowing by a film of water which is flowing as a thin film down a vertical plate. The H2S is being absorbed from the air to the water at a total pressure of 1.50 atm abs and 30oC. The value of kc of 9.567×10-4 m/s has been predicted for the gas-phase mass-transfer coefficient. At a given point the mole fraction of H2S in the liquid at the liquid-gas interface is 2.0×10-5 and pA of H2S in the gas is 0.05 atm. The Henry’s law equilibrium relation is pA(atm) = 609xA (mole fraction in liquid). Calculate the rate of absorption of H2S.
A
1.480×10-3 kmol/m2.s
B
1.486×10-3 kmol/m2.s
Saturated solution of benzene in water is in equilibrium with a mixture of air and vapours of benzene and water at room temperature and pressure. Mole fraction of benzene in liquid is x
B
and the vapour pressures of benzene and water at these conditions are P
v
B
and P
v
w
respectively. The partial pressure of benzene in air-vapour mixture is
A
P<sub>v</sub><sup>B</sup>
B
X<sub>B</sub>.P<sub>v</sub><sup>B</sup>
C
(P<sub>atm</sub> - P<sub>v</sub><sup>w</sup>)x<sub>B</sub>
D
X<sub>B</sub>.P<sub>atm</sub>
What is the total pressure exerted by a mixture of 0.45 kg mole of benzene, 0.44 kg mole of toluene and 0.23 kg mole of o-xylene at 100°C, if their vapor pressures at 100°C are 1340, 560 and 210 mmHg respectively?
A
756.2
B
780.5
C
801.5
D
880.5
Consider the following statements and choose the correct answer:
1. A direct proportionality exists between vapour pressure and the concentration of water vapour in the atmosphere
2. Relative humidity is an expression of the ratio of the actual vapour pressure of the atmosphere when saturated at the same temperature
3. A rise or fall in temperature with no change in vapour pressure will cause a drop or rise, respectively, in relative humidity
4. A rise or fall in vapour pressure with no change in temperature will be accompanied by a rise or fall, respectively, in relative humidity
A
1, 2, 3 and 4 are true
B
Only 3 and 4 are true
C
Only 2 and 4 are true
D
Only 1, 2 and 3 are true
Which of the following statements about partial pressure are correct? Statement 1: The partial pressure of each gas in a mixture is not proportional to its mole fraction.. Statement 2: The partial pressure of each gas is the product of the total pressure and the mole fraction of that gas.
A
True, False
B
True, True
C
False, True
D
False, False
In a gas mixture of hydrogen and oxygen, steady state equimolar counter diffusion is occurring at a total pressure of 100 kPa and temperature of 20°C. If the partial pressures of oxygen at two planes 0.01 m apart, and perpendicular to the direction of diffusion are 15 kPa and 5 kPa, respectively and the mass diffusion flux of oxygen in the mixture is 1.6 * 10–5 kmol/m2.sec, calculate the molecular diffusivity for the system. For equimolar counter current diffusion:
A
2.898×10-5 m2/sec
B
3.898×10-5 m2/sec
C
2.989×10-5 m2/sec
D
3.989×10-5 m2/sec
Consider an ideal vapour-liquid binary mixture, find the total pressure if the vapour pressure of A is 260 mmHg and the vapour pressure of B is 520 mmHg and the composition of A in mole fraction is 0.55.
A
177 mmHg
B
277 mmHg
C
377 mmHg
D
477 mmHg
What is the fraction of a gas in a system at partial pressure 1 atm, if the 0.1 fraction of the same gas is at partial pressure 2 atm and 0.2 fraction at partial pressure 4 atm (Use Freundlich Isotherm)?
A
0.01
B
0.03
C
0.05