Oil used to absorb benzene from gas is to be stripped with steam at P = 1atm to recover the benzene.Equlibrium at the operating temperature is approximated using Henry's Law.When the oil contains 10%mol of benzene,the oil's partial pressure is 5.07kPa.The oil is nonvolatile & enters with 8%mol benzene which 70% from that 8% is to be recovered. Steam leaving is 3%mol benzene.

How many theoretical stages are required?

My question here is,how to approximate the Henry's Law without knowing the temperature? I tried by using the partial pressure of oil given for 90% mol of oil(since 10%mol is benzene).Is my initial step correct? Need help asap,thanks

To approximate Henry's Law without knowing the temperature, you can make use of the given information at equilibrium. Henry's Law states that at a given temperature, the partial pressure of a gas above a liquid is directly proportional to the mole fraction of the gas in the liquid.

In this case, the oil contains 10% mol of benzene. So, at equilibrium, the partial pressure of benzene in the oil is given as 5.07 kPa. From this, you can calculate the mole fraction of benzene in the oil as follows:

Mole fraction of benzene in the oil = Partial pressure of benzene in the oil / Total pressure = 5.07 kPa / 101.3 kPa (since P = 1 atm = 101.3 kPa)

Now, since the mole fraction is directly proportional to the partial pressure, you can assume that the mole fraction of benzene in the oil will remain the same when the temperature is changed. Therefore, the mole fraction of benzene in the oil can be assumed to be the same as the mole fraction of benzene in the feed entering the system.

In the given information, it is mentioned that the feed oil contains 8% mol benzene. So, you can assume that the mole fraction of benzene in the oil is 8% mol.

Now that you have the mole fraction of benzene in the oil, you can proceed with the calculations to determine the number of theoretical stages required.