EXERCISES:1. A tank contains 100 ft3 of fresh water; 2 ft3 of brine, having a concentration of 1 pcf (1 lb/ft3) of salt, is run into the tank per minute, and the mixture, kept uniform by mixing, runs out at the rate of 1 ft3/min. What will be the exit brine concentration when the tank contains 150 ft3 of brine.

2. Three tanks of 25 m3 capacity are each arranged so that when water is fed into the first an equal quantity of solution overflows from the first to the second tank, likewise from the second to the third, and from the third to some point out of the system. Agitators keep the contents of each tank uniform in concentration. To start, let each of the tank be full of a salt solution of concentration 100 kg/m3. Run water into the first tank at 0.2 m3/min , and let the overflows functions as described above. Calculate the time required to reduce the salt concentration in the first tank to 10 kg/m3. Calculate the concentrations in the other two tanks at this time.

3. The consecutive, second order, irreversible reaction are carried out in a batch reactor:

One mole of A and two moles of S are initially added. Find the mole-fraction of X remaining in solution after half the A is consumed. Take k2/k1=2.

4. A tank 30 m3 in volume contains CO2 at pressure of 1000 kPa and temperature of 310 K. Suddenly, there is a small hole (leakage) in the tank. Gas flow rate through the hole at that time is 0.2 kgmole/hr. Then, the gas flow rate through the hole can be

obtained by the following equation, kgmoles/hr. Find the pressure in the tank 15 minutes after the leakage occurs.

5. Hemispherical tank of 1-meter diameter is initially full of volatile liquid. Vaporization rate of the liquid is proportional to liquid surface area. From the observation, it is known that the time required to decrease the liquid surface level height of 5 cm is 30 minutes. Derive an equation relating liquid volume in the tank and time.