Theoretical yield?

Question

Anyone know a quick formula for this that is easy to remember? Or a decent website to explain calculating theoretical yield.

Answer 1

There's not really any "formula" for this, but it's pretty simple if you understand it conceptually. What you need to do is find out what the limiting reagent is (the one with the fewest equivalents). This will give you the maximum theoreticaly moles of product you can get from the reaction. Then multiply this number by the mass of the product - this will give you the theoretical grams of product you can get from the reaction.
So here's the method:
1. Using the amounts (grams) of each starting reagent, divide these by the formula weights (grams/mole) for each reagent to get the moles of each. Do this for each reagent in the reaction.
2. Compare the moles of each that you're starting with. Whichever one you have the LEAST of, is your limiting reagent. The moles of this one are the maximum moles of product you can make.
3. Multiply the moles of the limiting reagent (from step 2) by the mass (formula weight) of the product. This will give you the theoretical yield (grams) of product.

Simple enough. Your actual yield is then the yield you get from the reaction divided by the theoretical yield.

The only tricky part you might encounter is in the first step - because you have to distinguish between moles and equivalents. For example, if you're using oxygen gas (O2) in the reaction, you have to recognize that there are two equivalents of O in there. So in the reaction of hydrogen and oxygen to make water, you have H2 + O2 = H2O, right? But you only need one equivalent of oxygen for every two equivalents of hydrogen. If you had equal moles of H2 and O2 in the reaction, hydrogen would be the limiting reaction - because you need two of those for every one oxygen. Sorry if that's confusing at all.

Answer 2

In organic chemistry the theoretical yeild is the expected yeild of a product if 100% conversion occured. Therefore if a for example you have a conversion, an oxidation of ethanol to acetic acid, 1 mole of ethanol will produce 1 mole of acetic acid i.e.

CH3CH2OH oxid to CH3COOH.

Therefore if you start out with 23g (0.5mole, Mol Weigth of CH3CH2OH = 46g/mol) will produce 0.5 moles Acetic acid. Since acetic acid molecular weight is 60g/mol then is you have 100% conversion your yeild will be 30g. This is a theoretical yeild since in most reactions you will not get 100% yeild (due to side reactions, presence of starting material, losing some in purification method etc) and only will get a percent of the theoretical yeild say 90% conversion.

So the steps to take are:

1. Write out the reaction, products as a balenced equation
2. Determine the number of moles of reactants available
3. Determine from the ratio of moles (obtained from you balenced equation) the amount of product that can be produced. This is your theoretical yeild of product

Hope this helps

Answer 3

Stand up each time you talk on the phone.

Answer 4

Teach your kids your best sport (or have them teach you theirs).

Answer 5

Skip waiting locations. When you have an appointment, check in and then go out for a walk until your receptionist phones you.

Answer 6

Yes. It's called a balanced chemical reaction equation.

Answer 7

When getting your hands on your kids from school, get free from the car and greet them that has a hug instead of waiting in the car curbside.

Answer 8

Dance on the radio or tap out a beat for the steering wheel while driving.

Answer 9

Take a lap around the grocery store before you begin shopping.

Answer 10

Wash your car as an alternative to taking it through the vehicle wash.