# Lab experiment

1. Nov 22, 2004

### apchemstudent

How can you improve the percent yield of an experiment? I'm not even sure what affects the percent yield. Please help.

2. Nov 22, 2004

### Sirus

$$\mbox{percent yield}=\frac{\mbox{experimental yield}}{\mbox{predicted yield}}\times 100$$

3. Nov 22, 2004

### apchemstudent

No, cuz that tells me nothing. All you're telling me is to improve my experimental yield, but i want to know ways of improving that.

4. Nov 23, 2004

### chem_tr

According to Le Chatelier's principle, reacting at least one of the products will increase the product yield; for example, if a reaction generates water, distilling it with toluene (an azeotropic mixture) at 80°C will drive your reaction to the right side.

All other applications may be explained with this very principle; taking the product into another non -miscible phase (for example, extraction is like that), or forcing it to precipitate (forming a solid phase in a solution), your yield will boost.

As a last word, try to produce inorganic reactants in an organic reaction; as the product will likely be insoluble in common organic solvents, your reaction will be of a good-yield one. Acetic anhydride may be prepared with acetic acid+dehydrating agent; but if you try to prepare with acetyl chloride+sodium acetate, your yield will be superior to the former.

I am sure you got the point.

5. Nov 23, 2004

### Sirus

Hmm. I see. I guess chem_tr covered it.

6. Nov 28, 2004

### pack_rat2

Some suggestions: 1) Increase the concentration of one of the reactants (the cheapest one, usually). That will cause more of the other reactant to react. 2) Choose conditions that push the equilibrium the right way; for instance, if 3 moles of gas react to form 2 moles of gas, higher pressure will favor the reaction. 3) Sometimes, a catalyst can be used.

7. Dec 1, 2004

### GCT

Assuming that this experiment is specific for a particular reaction and contains its own procedures.......simply follow the directions. You might want to tell us more details about your lab experiment.