Question

1. An aqueous solution of sulfuric acid (6M H2SO4 in water) is flowing into a tank at the

rate of 100 liters/min (also can be written 100 L/min) having a density of 1.34 g/cm3.

Calculate value of the items requested below and make sure you show HOW you

obtained them.

For parts (b) - (d), first write out the equation using symbols for the appropriate variables,

and then algebraically solve for the unknown variables, and finally substitute in the

numerical values and calculate the values for the unknown variables.

a) The molecular weight of the sulfuric acid.

b) The molar flow rate of into the tank.

c) The mass flow rate of into the tank.

d) The total mass flow rate into the tank.

2. Two organic vapors enter a separation column. One is benzene (C6H6), , and the other is toluene (C7H8), .

The total mass flow rate of the stream is 10,000 lbm/hr. The mass percent of benzene in the stream is 40%. Determine the following for the stream:

a) The mass flow rate of benzene.

b) The mass flow rate of toluene.

c) The molar flow rate of toluene.

d) The total molar flow rate of the stream.

e) The mole fraction of benzene.

Answer 1

1 lit solution contains 6 gram moles (98*6) = 588 g of H2 SO4.
a) So Molar flow rate of H2SO4 into the tank = 600 g moles / min

6M means that the concentration of acid is 6 mols/liter

b) is easy. 6 mols/L * 100 L/min = 600 mols/minute
the 'Ls' cancel out so the units are mols/minute.

for c) you have to find the atomic weight of H2SO4, which is 1 + 1 + 32.07+ 16+16+16+16 = 98 g/mol BUT there are 6 of them per liter. So the total mass is 588 grams/L. There are 100 L/min flowing, so we have 58,800 grams/minute of acid.

for d) you use the density of the solution for the total mass flow rate. There are 1000 cc/L, so the total mass/L is 1340 g/L. Again, the rate is 100 L/min, so the total mass flow is 134000 g/min