# Homework Help: Process Calculation

1. Jan 8, 2006

### siddharth

The question is
In the production of a drug having a molecular weight 192, the exit stream from the reactor flows at the rate of 10.3 L/min. The drug concentration is 41.2% (in water) and the specific gravity of the solution is 1.025. Calculate (i) The concentration of the drug in Kg/L in the exit stream
(ii) Flow rate in Kg-mol/min.

The question I have is

When the concentration of the drug is given as 41.2%, is it by mass or by volume? Is there any convention which is followed by engineers in this context? I ask this because in many similar problems, I have the same doubt.

2. Jan 8, 2006

### GCT

it's probably by weight percent, I'm not sure how well a molecule with such a high molecular weight would dissolve when it consists of almost 50% of the total volume.

3. Jan 9, 2006

### Moonbear

Staff Emeritus
When it is not specified to be by weight or volume (they really should specify this), you can usually assume they mean by weight when referring to a drug unless you have some reason to believe the pure form is a liquid at room temperature.

4. Jan 9, 2006

### Staff: Mentor

5. Jan 10, 2006

### siddharth

I asked my prof and he also said that unless it is specifed otherwise, I should take it as mass percentage.

Thanks for the help all.

6. Jan 10, 2006

### GCT

what does this have to do with anything in reference to the original post?

7. Feb 10, 2010

### smchauhdary

its solution is not too much difficult b/c you should solve in number of ways either my mass or by volume calculation