Yeild Help (1 Viewer)

[kazan]

can someone please explain how to get the estimated yeild please? we are dong it now and i dont understand

 

[Trebla]

Estimated yield or percentage yield?

Estimated yield is the AMOUNT of substance you EXPECT to obtain from a reaction.
e.g. the following synthesis reaction where 100mL of hydrogen gas molecules reacts with 100mL of chlorine gas molecules:

Chemical Equation: H2 + Cl2 --> 2HCl

Expected Volumes: 100mL + 100mL --> 200mL

The estimated yield of HCl you should obtain is 200mL.


Percentage yield is the the AMOUNT of substance you ACTUALLY OBTAIN as a PERCENTAGE of the amount of substance you EXPECT to obtain (as an estimated yield).
e.g. consider the same reaction:

Chemical Equation: H2 + Cl2 --> 2HCl

Expected Volumes: 100mL + 100mL --> 200mL

VOLUME OBTAINED: 100mL + 100mL --> 150mL

The estimated yield of HCl would still be 200mL.
The PERCENTAGE yield of HCl would be:
(150/200 x 100) = 75%

Remember this is the amount of HCl ONLY we are talking about.
The other 50mL may have been lost by leakage or incomplete reactions etc.

Correct me if I'm wrong, but I hope it helps.

 

[Jumbo Cactuar]

Yield usually is a factor in organic chemisty. Consider the production of amphetamines; it has 22 distinct stages ~ you start with kilos and kilos of stuff only to make less than a gram. Don't quote me on that, I don't know first hand.

It is usually because of an equilibria that you get shitty yield (ie ammonia production from hydrogen and nitrogen is approx 22% yield).

For yield calculations you can use any quantity that directly relates to the amount under fixed conditions. It is simply;

amount you produced * 100%
amount you expect

Roughly speaking the above example works.

A better example though.