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In an accident a container containing ethanol(s.g 0.789) falls down in a room of dimension 1*1*2(all in m). Ethanol forms a layer of 2mm. Ethanol vaporizes and diffuses through a stagnant film of air of thickness 2.5mm. What will be the time required for the water layer to disappear completely. The diffusivity of ethanol in air is 2.567*10-5 m2/s. the total pressure is 1.013 bar and the pressure of ethanol in bulk air is 0.02244 bar and at the ethanol-air interface is 0.02718bar. The temperature is 25.2°C.

Correct Answer: 4.73h
This is the case of diffusion of through non diffusing B. NA=DP/RTZ*ln⁡ NA=(2.567*10-5*1.013)/(0.08317*298.2*2.5*10-3)*ln⁡ = 2.01*10-6 kmol/m2.s=9.259*10-5kg/m2.s Amount of ethanol = 2*10-3*1=0.002m3=1.578kg Time for evaporation= 1.578/9.259*10-5=17042.87s=4.73h.

Oxygen diffuses through a stagnant layer of air, 1mm thick, ambient temperature 28°C and 1atm total pressure. The partial pressure of oxygen on two sides of layer is P1=0.9atm and P2=0.1atm respectively. Calculate the value of Molar flux (in mol/m2.s) with respect to an observer moving with molar average velocity. Calculate this value at the end of the path where P2=0.1atm. Use R=8.205*10-5m3atmK-1mol-1.

Pure aniline is evaporating through a stagnant air film of 1 mm thickness at 300 K and a total pressure of 100 KPa. The vapor pressure of aniline at 300 K is 0.1 KPa. The total molar concentration under these conditions is 40.1 mole/m3. The diffusivity of aniline in air is 0.74 × 10-5 m2/s.The numerical value of mass transfer co-efficient is 7.4 × 10-3. The rate of evaporation of aniline is 2.97 × 10-4. Its units are

Pure aniline is evaporating through a stagnant air film of 1 mm thickness at 300 K and a total pressure of 100 KPa. The vapor pressure of aniline at 300 K is 0.1 KPa. The total molar concentration under these conditions is 40.1 mole/m3. The diffusivity of aniline in air is 0.74 × 10-5 m2/s. The numerical value of mass transfer co-efficient is 7.4 × 10-3. Its units are

It takes 5 hours to fill a container using machine A. The same container can be filled using machine B in 10 hours. When the container is full, Machine C can fully empty the container in 20 hours. If all three machines start working on the same empty container how long will it take for the container to be completely filled,

From container A containing 54 liter of mixture of milk and water in ratio of 8 : 1 , 18 liter of the mixture is taken out and poured into container B in which ratio of milk to water is 3 : 1. If difference between total milk and total water in container B is 30 liter then find the quantity of initial mixture in container B.

Hotel Aditya has 10 single AC rooms, 5 double AC rooms and 18 non AC rooms. The fixed monthly rent of hotel is 150,000. The per day maintenance cost is Rs. 100 for double AC room, Rs. 75 for single AC room and Rs. 40 for non AC room. The per day charges are Rs. 600 for double AC room, Rs. 400 for single AC room and Rs. 250 for non AC room. In April 2003, the occupancy rate of non AC room was 50%, 70% of single AC room and 40% of double AC rooms. Find the profit/loss % for that particular month.

A steel bar 600mm long and having 30mm diameter, is turned down to 25mm diameter for one fourth of its length. It is heated at 30 C above room temperature, clamped at both ends and then allowed to cool to room temperature. If the distance between the clamps is unchanged, the maximum stress in the bar ( α = 12.5 x 10-6 per C and E = 200 GN/m2) is

There are two containers, the first one contains 1 litre pure water and the second one contains 1 litre pure milk.Now 5 cups of water from the first container is taken out is mixed well in the second container. Then, 5 cups of this mixture is taken out and is mixed in the first container. Let A denote the proportion of milk in the first container and B denote the proportion of water in the second container then:

Calculate the total flux of A-atoms across a stationary plane with respect to the specimen from the following parameters? Diffusive flux is given as 3 (moles/m2s) Flux due to velocity of the lattice is given as 4(moles/m2s)

Statement 1: When heat transfer takes between a solid surface and a fluid, an insulating film layer is formed. More is the agitation; more is the thickness of the film. Statement 2: Within the film, the temperature varies from the wall to the temperature of the bulk.